Materiały źródłowe

• #1

  http://pat.zsmu.edu.ua/article/view/22589

  The occurrence of pilonidal cysts in Ukrainian population is up to 50 cases per 100.000. Nevertheless, the cause and the pathogenesis of pilonidal cyst to date remain unclear. […] Authors suggest the definite answer should be based primarily on the results of the morphologic evaluation of pilonidal cyst tissue. […] The absence of own epithelial elements in the pilonidal cysts and the secondary sinus tracts have been demonstrated. Hypertrophic growth of skin or hair follicle epithelium was evident in some specimens. Such changes seen in the deep layers of skin on the border with adipose tissue were similar to epidermal polyps. […] There are some morphological features suggesting the acquired origin of the pilonidal disease as follows: […] Pilonidal cyst doesnt have own epithelium, and the epithelial fragments that occur are the fragments of disorganized hair follicles.

• #2 Pilonidal sinus disease: a misunderstood problem – Wounds UK

  https://wounds-uk.com/journal-articles/pilonidal-sinus-disease-a-misunderstood-problem-1/

  Pilonidal sinus disease, although relatively rare, is still poorly understood both in terms of pathophysiology or the best treatment options. […] This article will, through an exploration of the literature, highlight the pathogenesis of pilonidal sinus disease, patient characteristics, presenting factors, conservative and surgical options, and management choices for the treatment of wounds healing by secondary intention.

• #3 Pilonidal Cyst and Sinus – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557770/

  Pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease, suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time. […] Karydakis simplified the description of the etiologic process citing three main factors – the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability. […] The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #4 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #5 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  Early after its description, many clinicians considered the disease as congenital in origin, being derived from vestiges of the medullary tube, dermoid traction, inclusion dermoid, or preen glands. Currently, pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease, suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time. […] Karydakis simplified the description of the etiologic process citing three main factors- the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability.

• #6 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  Pilonidal disease is now considered an acquired condition of the hair follicles. […] The central pathological event in these conditions is thought to be follicular hyperkeratosis, leading to obstruction of the infundibulum of a hair follicle. […] The follicle becomes dilated and ruptures, leading to secondary infection and the formation of fistulae and abscesses. […] Karydakis already hypothesized in the 1970s that fistulae arise only when free hairs perforate the vulnerable, but still intact skin. […] The hairs that are found in the subcutaneous sinus cavity seem to be broken or cut head and neck hairs, i.e., hairs that have been separated from their follicles. […] Karydakis suspected that they become implanted in the natal cleft and then bore deeper and deeper into the subcutaneous tissue, in the manner of a screw.

• #7 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  The origin of the pilonidal sinus is controversial with two main theories. The congenital theory was initially popular and suggested that a remnant of the medullary canal with infolding of the surface epithelium or a faulty coalescence of the cutaneous covering in early embryonic life led to pilonidal sinus development. […] The acquired theory is now widely accepted, but its mechanisms are speculative and varied. Bascom believes the affected hair follicles become distended with keratin and subsequently infected, leading to folliculitis and the formation of an abscess that extends down into the subcutaneous fat. […] Karydakis, on the other hand, believes the shaft of loose hair, because of its scales with chisel-like root ends, inserts into the depth of the natal cleft in the midline of sacrococcygeal area.

• #8 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Pilonidal disease is an infection under the skin in the gluteal cleft. Pilonidal literally means a nest of hair. […] The disease was initially thought to be congenital, due to the failure of fusion in the dorsal midline resulting in entrapment of hair follicles in the sacrococcygeal region; however, more recent research strongly favors an acquired etiology. […] Several findings support an acquired etiology. Occupation may play a role. Interestingly, pilonidal disease has been reported to occur between the fingers of sheep shearers, dog groomers, cow milkers, and barbers. […] The acquired theory is further supported by Bascom who notes that hair follicles in the gluteal cleft become infected with keratin resulting in local infection and abscess formation while local suction forces cause hairs to enter the infected pit and lodge in the abscess cavity.

• #9 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #10 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  The keratin flakes of these hairs function as barbs that permit movement in one direction only. […] This theory clearly diverges from the theory of hyperkeratosis and follicular occlusion. […] Brearley showed experimentally that movement of the gluteal musculature leads to negative pressure in the pilonidal sinus, drawing the free hairs inward. […] Nonetheless, the fact that pilonidal disease can arise in the interdigital space of hairdressers seems rather to confirm the theory of Karydakis. […] In the 1930s, the sinus was thought to be an epithelialized cyst, and the notion therefore arose that the condition is congenital. […] Later, however, Patey and others showed that the subcutaneous cavity is actually lined by granulation tissue.

• #11

  http://pat.zsmu.edu.ua/article/view/22589

  The occurrence of pilonidal cysts in Ukrainian population is up to 50 cases per 100.000. Nevertheless, the cause and the pathogenesis of pilonidal cyst to date remain unclear. […] Authors suggest the definite answer should be based primarily on the results of the morphologic evaluation of pilonidal cyst tissue. […] The absence of own epithelial elements in the pilonidal cysts and the secondary sinus tracts have been demonstrated. Hypertrophic growth of skin or hair follicle epithelium was evident in some specimens. Such changes seen in the deep layers of skin on the border with adipose tissue were similar to epidermal polyps. […] There are some morphological features suggesting the acquired origin of the pilonidal disease as follows: […] Pilonidal cyst doesnt have own epithelium, and the epithelial fragments that occur are the fragments of disorganized hair follicles.

• #12 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #13 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #14 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Pilonidal disease is an infection under the skin in the gluteal cleft. Pilonidal literally means a nest of hair. […] The disease was initially thought to be congenital, due to the failure of fusion in the dorsal midline resulting in entrapment of hair follicles in the sacrococcygeal region; however, more recent research strongly favors an acquired etiology. […] Several findings support an acquired etiology. Occupation may play a role. Interestingly, pilonidal disease has been reported to occur between the fingers of sheep shearers, dog groomers, cow milkers, and barbers. […] The acquired theory is further supported by Bascom who notes that hair follicles in the gluteal cleft become infected with keratin resulting in local infection and abscess formation while local suction forces cause hairs to enter the infected pit and lodge in the abscess cavity.

• #15 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  The keratin flakes of these hairs function as barbs that permit movement in one direction only. […] This theory clearly diverges from the theory of hyperkeratosis and follicular occlusion. […] Brearley showed experimentally that movement of the gluteal musculature leads to negative pressure in the pilonidal sinus, drawing the free hairs inward. […] Nonetheless, the fact that pilonidal disease can arise in the interdigital space of hairdressers seems rather to confirm the theory of Karydakis. […] In the 1930s, the sinus was thought to be an epithelialized cyst, and the notion therefore arose that the condition is congenital. […] Later, however, Patey and others showed that the subcutaneous cavity is actually lined by granulation tissue.

• #16 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Karydakis asserts that loose hairs impale into otherwise normal tissue and induce a foreign body reaction. Secondary pits then result from subcutaneous burrowing of hair and additional hairs enter through the pits. […] His work in over 6000 patients led him to devise a pathogenic formula involving three primary variables: (1) loose hair or invader (H) applies some (2) force (F), which is influenced by secondary factors such as the depth, narrowness, and friction of the natal cleft to create an insertion process. The third factor of vulnerability, (V), refers to the local skin and tissues. In this model the primary sinuses represent the hair entry sites and secondary sinuses represent the exit points. […] Kitchen outlined a sequence of factors that describe the formation of a pilonidal sinus.

• #17 Pilonidal Cyst and Sinus – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557770/

  Pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease, suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time. […] Karydakis simplified the description of the etiologic process citing three main factors – the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability. […] The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #18 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  The origin of the pilonidal sinus is controversial with two main theories. The congenital theory was initially popular and suggested that a remnant of the medullary canal with infolding of the surface epithelium or a faulty coalescence of the cutaneous covering in early embryonic life led to pilonidal sinus development. […] The acquired theory is now widely accepted, but its mechanisms are speculative and varied. Bascom believes the affected hair follicles become distended with keratin and subsequently infected, leading to folliculitis and the formation of an abscess that extends down into the subcutaneous fat. […] Karydakis, on the other hand, believes the shaft of loose hair, because of its scales with chisel-like root ends, inserts into the depth of the natal cleft in the midline of sacrococcygeal area.

• #19 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  Pilonidal disease is now considered an acquired condition of the hair follicles. […] The central pathological event in these conditions is thought to be follicular hyperkeratosis, leading to obstruction of the infundibulum of a hair follicle. […] The follicle becomes dilated and ruptures, leading to secondary infection and the formation of fistulae and abscesses. […] Karydakis already hypothesized in the 1970s that fistulae arise only when free hairs perforate the vulnerable, but still intact skin. […] The hairs that are found in the subcutaneous sinus cavity seem to be broken or cut head and neck hairs, i.e., hairs that have been separated from their follicles. […] Karydakis suspected that they become implanted in the natal cleft and then bore deeper and deeper into the subcutaneous tissue, in the manner of a screw.

• #20 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  The origin of the pilonidal sinus is controversial with two main theories. The congenital theory was initially popular and suggested that a remnant of the medullary canal with infolding of the surface epithelium or a faulty coalescence of the cutaneous covering in early embryonic life led to pilonidal sinus development. […] The acquired theory is now widely accepted, but its mechanisms are speculative and varied. Bascom believes the affected hair follicles become distended with keratin and subsequently infected, leading to folliculitis and the formation of an abscess that extends down into the subcutaneous fat. […] Karydakis, on the other hand, believes the shaft of loose hair, because of its scales with chisel-like root ends, inserts into the depth of the natal cleft in the midline of sacrococcygeal area.

• #21 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Pilonidal disease is an infection under the skin in the gluteal cleft. Pilonidal literally means a nest of hair. […] The disease was initially thought to be congenital, due to the failure of fusion in the dorsal midline resulting in entrapment of hair follicles in the sacrococcygeal region; however, more recent research strongly favors an acquired etiology. […] Several findings support an acquired etiology. Occupation may play a role. Interestingly, pilonidal disease has been reported to occur between the fingers of sheep shearers, dog groomers, cow milkers, and barbers. […] The acquired theory is further supported by Bascom who notes that hair follicles in the gluteal cleft become infected with keratin resulting in local infection and abscess formation while local suction forces cause hairs to enter the infected pit and lodge in the abscess cavity.

• #22 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #23 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #24 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #25 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  Pilonidal disease is now considered an acquired condition of the hair follicles. […] The central pathological event in these conditions is thought to be follicular hyperkeratosis, leading to obstruction of the infundibulum of a hair follicle. […] The follicle becomes dilated and ruptures, leading to secondary infection and the formation of fistulae and abscesses. […] Karydakis already hypothesized in the 1970s that fistulae arise only when free hairs perforate the vulnerable, but still intact skin. […] The hairs that are found in the subcutaneous sinus cavity seem to be broken or cut head and neck hairs, i.e., hairs that have been separated from their follicles. […] Karydakis suspected that they become implanted in the natal cleft and then bore deeper and deeper into the subcutaneous tissue, in the manner of a screw.

• #26 Pilonidal Sinus – Clinical Features – Management – TeachMeSurgery

  https://teachmesurgery.com/general/anorectal/pilonidal-sinus/

  Pilonidal sinus disease is a disease of the inter-gluteal region, characterised by the formation of a sinus in the cleft of the buttocks. It most commonly affects males aged 16-30 years. The most widely accepted theory for pilonidal sinus disease development begins with a hair follicle in the intergluteal cleft becoming infected or inflamed. This inflammation obstructs the opening of the follicle, which extends inwards, forming a pit (a characteristic feature of pilonidal sinus disease). A foreign body-type reaction may then lead to formation of a cavity, connected to the surface of the skin by an epithelialised sinus tract. These fluid-filled cavities (cysts) will often discharge serous fluid and can periodically become acutely infected to form a pilonidal abscess. […] Pilonidal sinus disease occurs from the infection or inflammation of hair follicles in the cleft of the buttocks.

• #27 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  The origin of the pilonidal sinus is controversial with two main theories. The congenital theory was initially popular and suggested that a remnant of the medullary canal with infolding of the surface epithelium or a faulty coalescence of the cutaneous covering in early embryonic life led to pilonidal sinus development. […] The acquired theory is now widely accepted, but its mechanisms are speculative and varied. Bascom believes the affected hair follicles become distended with keratin and subsequently infected, leading to folliculitis and the formation of an abscess that extends down into the subcutaneous fat. […] Karydakis, on the other hand, believes the shaft of loose hair, because of its scales with chisel-like root ends, inserts into the depth of the natal cleft in the midline of sacrococcygeal area.

• #28 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  Pilonidal disease is now considered an acquired condition of the hair follicles. […] The central pathological event in these conditions is thought to be follicular hyperkeratosis, leading to obstruction of the infundibulum of a hair follicle. […] The follicle becomes dilated and ruptures, leading to secondary infection and the formation of fistulae and abscesses. […] Karydakis already hypothesized in the 1970s that fistulae arise only when free hairs perforate the vulnerable, but still intact skin. […] The hairs that are found in the subcutaneous sinus cavity seem to be broken or cut head and neck hairs, i.e., hairs that have been separated from their follicles. […] Karydakis suspected that they become implanted in the natal cleft and then bore deeper and deeper into the subcutaneous tissue, in the manner of a screw.

• #29 Pilonidal cyst – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/pilonidal-cyst/symptoms-causes/syc-20376329

  A pilonidal cyst is an unusual pocket in the skin that usually contains hair and skin debris. Pilonidal cysts usually occur when hair punctures the skin and then becomes embedded. […] The cause of most pilonidal cysts is loose hairs that puncture the skin. Friction and pressure from rubbed skin, tight clothing, cycling or long periods of sitting can force hair into the skin. […] The body creates a cyst around the hair to try to push it out. Most pilonidal cysts form on the tailbone.

• #30 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  Pilonidal disease is now considered an acquired condition of the hair follicles. […] The central pathological event in these conditions is thought to be follicular hyperkeratosis, leading to obstruction of the infundibulum of a hair follicle. […] The follicle becomes dilated and ruptures, leading to secondary infection and the formation of fistulae and abscesses. […] Karydakis already hypothesized in the 1970s that fistulae arise only when free hairs perforate the vulnerable, but still intact skin. […] The hairs that are found in the subcutaneous sinus cavity seem to be broken or cut head and neck hairs, i.e., hairs that have been separated from their follicles. […] Karydakis suspected that they become implanted in the natal cleft and then bore deeper and deeper into the subcutaneous tissue, in the manner of a screw.

• #31 Pilonidal Cyst and Sinus – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557770/

  Pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease, suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time. […] Karydakis simplified the description of the etiologic process citing three main factors – the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability. […] The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #32 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  Once one hair inserts successfully, other hairs can insert more easily. Foreign body tissue reaction and infection follow, and the primary sinus of pilonidal disease forms. […] Isolated reports of pilonidal sinus occurring in unusual locations, such as the umbilicus, a healed amputation stump, and interdigital clefts, and the recurrence of the disease in an adequately excised area support the acquired theory of this disease and Karydakiss concept of hair insertion.

• #33

  http://pat.zsmu.edu.ua/article/view/22589

  In the pilonidal cysts tissues immunopathological cell reactions of foreign body rejection are evident. Disorganization and lysis of hair shafts, vessel hyalinosis, fibrinoid degeneration and lymphoid cells infiltration are critical components of pilonidal cysts morphogenesis. […] The important role in the consistent development of pathogenetic mechanisms of sinus ducts formation in sacrococcygeal pilonidal disease is played by common pathological mechanisms of tubular sinus ducts formation with hypertrophic skin epithelium growth in the external sinus tract area and on the fundus of enlarged hair follicle with epithelial polyp formation. […] Pilonidal disease has an acquired origin and develops when the loose hair shafts penetrate into skin through the destroyed hair follicles in the intergluteal cleft.

• #34 Approach to Interdigital Pilonidal Sinus: Our Clinical Experience and Literature Review | ClinMed International Library | International Journal of Surgery Research and Practice

  https://clinmedjournals.org/articles/ijsrp/international-journal-of-surgery-research-and-practice-ijsrp-3-042.php?jid=ijsrp

  Interdigital pilonidal sinus disease, also called „barber’s disease,” is an acquired occupational disease. […] Although the etiology has not been fully clarified, the disease is thought to be mostly caused by the formation of an acute and chronic infection focus under the skin by hair shed from the skin. […] The histological structure of interdigital pilonidal sinus disease (IPSD) observed in barbers was defined as a foreign body granuloma for the first time in 1942 by Templeton. […] IPSD is now generally accepted as an acquired disease independent of body location. […] In addition, IPSD is known as an occupational disease among barbers because the sinuses develop a foreign body reaction against customers’ hair. […] The disease progresses with the formation of a sinus and eventually a cyst.

• #35 Approach to Interdigital Pilonidal Sinus: Our Clinical Experience and Literature Review | ClinMed International Library | International Journal of Surgery Research and Practice

  https://clinmedjournals.org/articles/ijsrp/international-journal-of-surgery-research-and-practice-ijsrp-3-042.php?jid=ijsrp

  Histological studies on samples of pilonidal sinus disease reveal that hair fragments that penetrate the skin are first surrounded by nonspecific inflammatory infiltrate and granulomas and then develop a foreign body granulomatous reaction. […] The best method to treat this disease and prevent recurrence is protection. […] Granulation tissue that develops in the wound during the postoperative period eventually becomes scar tissue containing inactive fibroblasts, intensive collagen fibrils, elastic tissue fragments, extracellular matrix, and a few vessels.

• #36 Pilonidal disease – Knowledge @ AMBOSS

  https://www.amboss.com/us/knowledge/pilonidal-disease/

  The exact mechanism is unknown, however, the current prevailing hypothesis is that pilonidal disease is an acquired condition. […] Sitting or bending cause hair follicles, in vulnerable skin within a deep gluteal cleft, to stretch and break formation of an open pore or pit. These open pores either collect debris or broken hair roots (from the head, back or buttocks). […] Movement causes negative pressure (e.g., suction effect) and further penetration of hair into local subcutaneous tissue formation of a pilonidal sinus. […] These collections trigger local tissue inflammation within the pilonidal sinus acute infection (abscess) or fistulae.

• #37 Pilonidal Cyst and Sinus: Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/788127-overview

  It has been postulated that hair penetrates into the subcutaneous tissues through dilated hair follicles, which is thought to occur particularly in late adolescence, though follicles are not found in the walls of cysts. Upon sitting or bending, hair follicles can break and open a pit. Debris may collect in this pit, followed by development of a sinus with a short tract, with a not clearly understood suction mechanism involving local anatomy, eventually leading to further penetration of the hair into the subcutaneous tissue. […] A foreign body-type reaction may then lead to formation of an abscess. If given the opportunity to drain spontaneously, this may act as a portal of further invasion and eventually formation of a foreign body granuloma. Infection may result in abscess formation. Increased sweat may also contribute to development of a cyst and sinus. […] In summary, 3 pieces are instrumental in this process: (1) the invader, hair; (2) the force, causing hair penetration; and (3) the vulnerability of the skin.

• #38 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Loose hairs are drilled, propelled, and sucked into the pilonidal sinus by friction and the movement of the buttocks whenever a patient stands or sits. This bending and sitting action tightens the skin of the gluteal cleft and lifts it from the fascia. The negative pressure drives hair deeper into the sinus and appears to be exaggerated with a deep gluteal cleft. […] Hair enters tip first, and the barbs on the hair prevent it from being expelled, causing the hair to become entrapped. Physical examination occasionally may reveal a tuft of hair emerging from the midline opening in the natal cleft. This trapped hair stimulates a foreign body reaction and infection. Rarely, foreign bodies other than human hair can cause this disease process. Rare case reports exist in which the hair did not come from the patient but instead came from a bird’s feather, the type used to stuff feather bedding.

• #39 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  The keratin flakes of these hairs function as barbs that permit movement in one direction only. […] This theory clearly diverges from the theory of hyperkeratosis and follicular occlusion. […] Brearley showed experimentally that movement of the gluteal musculature leads to negative pressure in the pilonidal sinus, drawing the free hairs inward. […] Nonetheless, the fact that pilonidal disease can arise in the interdigital space of hairdressers seems rather to confirm the theory of Karydakis. […] In the 1930s, the sinus was thought to be an epithelialized cyst, and the notion therefore arose that the condition is congenital. […] Later, however, Patey and others showed that the subcutaneous cavity is actually lined by granulation tissue.

• #40 Pilonidal cyst – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/pilonidal-cyst/symptoms-causes/syc-20376329

  A pilonidal cyst is an unusual pocket in the skin that usually contains hair and skin debris. Pilonidal cysts usually occur when hair punctures the skin and then becomes embedded. […] The cause of most pilonidal cysts is loose hairs that puncture the skin. Friction and pressure from rubbed skin, tight clothing, cycling or long periods of sitting can force hair into the skin. […] The body creates a cyst around the hair to try to push it out. Most pilonidal cysts form on the tailbone.

• #41 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Loose hairs are drilled, propelled, and sucked into the pilonidal sinus by friction and the movement of the buttocks whenever a patient stands or sits. This bending and sitting action tightens the skin of the gluteal cleft and lifts it from the fascia. The negative pressure drives hair deeper into the sinus and appears to be exaggerated with a deep gluteal cleft. […] Hair enters tip first, and the barbs on the hair prevent it from being expelled, causing the hair to become entrapped. Physical examination occasionally may reveal a tuft of hair emerging from the midline opening in the natal cleft. This trapped hair stimulates a foreign body reaction and infection. Rarely, foreign bodies other than human hair can cause this disease process. Rare case reports exist in which the hair did not come from the patient but instead came from a bird’s feather, the type used to stuff feather bedding.

• #42 Pilonidal Cyst and Sinus – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557770/

  Pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease, suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time. […] Karydakis simplified the description of the etiologic process citing three main factors – the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability. […] The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #43 The Management of Pilonidal Sinus (07.01.2019)

  https://di.aerzteblatt.de/int/archive/article/204214

  The keratin flakes of these hairs function as barbs that permit movement in one direction only. […] This theory clearly diverges from the theory of hyperkeratosis and follicular occlusion. […] Brearley showed experimentally that movement of the gluteal musculature leads to negative pressure in the pilonidal sinus, drawing the free hairs inward. […] Nonetheless, the fact that pilonidal disease can arise in the interdigital space of hairdressers seems rather to confirm the theory of Karydakis. […] In the 1930s, the sinus was thought to be an epithelialized cyst, and the notion therefore arose that the condition is congenital. […] Later, however, Patey and others showed that the subcutaneous cavity is actually lined by granulation tissue.

• #44 Pilonidal Cyst and Sinus – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557770/

  Pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease, suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time. […] Karydakis simplified the description of the etiologic process citing three main factors – the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability. […] The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #45 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #46 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #47 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Additionally, the depth of the natal cleft is a developmental factor. Akinci and colleagues studied 50 patients undergoing surgery for pilonidal disease and 51 healthy volunteers who had their natal clefts measured with a specially designed device. They observed significantly deeper natal clefts in patients with pilonidal disease. […] Although often described incorrectly as a cyst, pilonidal cavities are not true cysts and lack a fully epithelialized lining; however, the fibrous tracts of the sinus may be epithelialized. Pilonidal sinus or disease is therefore the correct term. The majority of sinus tracts extend cephalad; however, additional sinuses may branch laterally. […] Interestingly, hair follicles are rarely seen on pathologic examination. Cavities may contain hair, debris, and granulation tissue. The local cellular infiltration is sizable and often includes foreign body giant cells in association with hair.

• #48 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #49 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #50 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #51 Pilonidal Cyst and Sinus | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/27223

  The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above). […] Microscopically its noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

• #52 Pilonidal Cyst: Firm Nodule Near Anus – Dermatology Advisor

  https://www.dermatologyadvisor.com/ddi/pilonidal-cyst/

  The pathophysiology of the disease is unclear but it is hypothesized that inversion of hair growth leads to a foreign-body reaction resulting in granuloma formation. […] Risk factors include obesity, poor hygiene, coarse hair, prolonged friction, and coexisting hidradenitis suppurativa. […] Excising the abscess cavity and thoroughly removing the nest of hair and skin debris has been demonstrated to reduce recurrence and complications from wound healing.

• #53 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Additionally, the depth of the natal cleft is a developmental factor. Akinci and colleagues studied 50 patients undergoing surgery for pilonidal disease and 51 healthy volunteers who had their natal clefts measured with a specially designed device. They observed significantly deeper natal clefts in patients with pilonidal disease. […] Although often described incorrectly as a cyst, pilonidal cavities are not true cysts and lack a fully epithelialized lining; however, the fibrous tracts of the sinus may be epithelialized. Pilonidal sinus or disease is therefore the correct term. The majority of sinus tracts extend cephalad; however, additional sinuses may branch laterally. […] Interestingly, hair follicles are rarely seen on pathologic examination. Cavities may contain hair, debris, and granulation tissue. The local cellular infiltration is sizable and often includes foreign body giant cells in association with hair.

• #54 Pilonidal Cyst: Firm Nodule Near Anus – Dermatology Advisor

  https://www.dermatologyadvisor.com/ddi/pilonidal-cyst/

  The pathophysiology of the disease is unclear but it is hypothesized that inversion of hair growth leads to a foreign-body reaction resulting in granuloma formation. […] Risk factors include obesity, poor hygiene, coarse hair, prolonged friction, and coexisting hidradenitis suppurativa. […] Excising the abscess cavity and thoroughly removing the nest of hair and skin debris has been demonstrated to reduce recurrence and complications from wound healing.

• #55 Pilonidal sinus

  https://www.nhs.uk/conditions/pilonidal-sinus/

  It’s not clear what causes a pilonidal sinus. […] A skin problem, pressure or friction may cause hair between the buttocks to be pushed inwards. […] This may either be hair growing around the buttock area, or loose hair shed from the buttocks or elsewhere that gathers around the buttock cleft and enters the pilonidal sinus. […] Pilonidal sinuses are more common in men because they tend to be hairier. […] Sitting for long periods can also increase your chances of getting a pilonidal sinus.

• #56 Pilonidal Disease: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/192668-overview

  Pilonidal disease is now widely considered to be an acquired disorder, on the basis of observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The pilonidal cyst is also not a true cyst, in that it has an epithelialized walls and is more of a cavity, which makes a congenital origin less likely. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis. […] After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. In pilonidal disease, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep subcutaneous cavity.

• #57 Pilonidal Sinus Disease (Pilonidal Cyst) – Dermatology Advisor

  https://www.dermatologyadvisor.com/home/decision-support-in-medicine/dermatology/pilonidal-sinus-disease-pilonidal-cyst/

  It is only those men and women who have a predisposing morphologic shape and curvature of their buttocks and who routinely create rhythmical, shearing movements with their lower backs and buttocks in their occupation and normal daily activities who will develop PSD. […] It has been suggested that gravity and intergluteal motion together create a type of vacuum that directs loose hair into the funnel of the pilonidal sinus.

• #58 Pilonidal sinus

  https://www.nhs.uk/conditions/pilonidal-sinus/

  It’s not clear what causes a pilonidal sinus. […] A skin problem, pressure or friction may cause hair between the buttocks to be pushed inwards. […] This may either be hair growing around the buttock area, or loose hair shed from the buttocks or elsewhere that gathers around the buttock cleft and enters the pilonidal sinus. […] Pilonidal sinuses are more common in men because they tend to be hairier. […] Sitting for long periods can also increase your chances of getting a pilonidal sinus.

• #59 Pilonidal Cyst: Firm Nodule Near Anus – Dermatology Advisor

  https://www.dermatologyadvisor.com/ddi/pilonidal-cyst/

  The pathophysiology of the disease is unclear but it is hypothesized that inversion of hair growth leads to a foreign-body reaction resulting in granuloma formation. […] Risk factors include obesity, poor hygiene, coarse hair, prolonged friction, and coexisting hidradenitis suppurativa. […] Excising the abscess cavity and thoroughly removing the nest of hair and skin debris has been demonstrated to reduce recurrence and complications from wound healing.

• #60 Pilonidal Cyst: Firm Nodule Near Anus – Dermatology Advisor

  https://www.dermatologyadvisor.com/ddi/pilonidal-cyst/

  The pathophysiology of the disease is unclear but it is hypothesized that inversion of hair growth leads to a foreign-body reaction resulting in granuloma formation. […] Risk factors include obesity, poor hygiene, coarse hair, prolonged friction, and coexisting hidradenitis suppurativa. […] Excising the abscess cavity and thoroughly removing the nest of hair and skin debris has been demonstrated to reduce recurrence and complications from wound healing.

• #61 Pilonidal disease – Wikipedia

  https://en.wikipedia.org/wiki/Pilonidal_disease

  Pilonidal cysts may be caused by a congenital pilonidal dimple. […] The underlying mechanism is believed to involve a mechanical process where hair and skin debris get sucked into the subcutaneous tissues through skin openings called pits. […] Excessive sweating can also contribute to the formation of a pilonidal cyst: moisture can fill a stretched hair follicle, which helps create a low-oxygen environment that promotes the growth of anaerobic bacteria, often found in pilonidal cysts. The presence of bacteria and low oxygen levels hamper wound healing and exacerbate a developing pilonidal cyst.

• #62 Rethinking the causes of pilonidal sinus disease: a matched cohort study | Scientific Reports

  https://www.nature.com/articles/s41598-021-85830-1

  Our understanding of pilonidal sinus disease (PSD) is based on a paper published 29 years ago by Karydakis. […] Thus sweating may have a protective effect in PSD rather than being a risk factor. […] However, the pathomechanism of PSD has never been fully clarified. […] For decades surgeons have assumed that maceration of the IGF is a risk factor for PSD and that pilonidal patients sweat more than people without the disease. Our analysis adjusting for confounding disproves this. […] Thus our findings overturn long-standing assumptions about the genesis of PSD. […] If the IGF were totally dry, no hair would be retained by adhesion. […] However, we did not see any of these effects in our German PSD cohort. […] Three different statistical techniques that adjust for confounding consistently demonstrated less sweating in PSD patients. […] Our findings present a different picture of pilonidal disease than the one provided by Karydakis. […] Future research into PSD should focus on skin texture changes, hormonal changes during puberty, age-related sweating, hair strength, and skin-to-hair-strength ratio changes.

• #63

  http://pat.zsmu.edu.ua/article/view/22589

  In the pilonidal cysts tissues immunopathological cell reactions of foreign body rejection are evident. Disorganization and lysis of hair shafts, vessel hyalinosis, fibrinoid degeneration and lymphoid cells infiltration are critical components of pilonidal cysts morphogenesis. […] The important role in the consistent development of pathogenetic mechanisms of sinus ducts formation in sacrococcygeal pilonidal disease is played by common pathological mechanisms of tubular sinus ducts formation with hypertrophic skin epithelium growth in the external sinus tract area and on the fundus of enlarged hair follicle with epithelial polyp formation. […] Pilonidal disease has an acquired origin and develops when the loose hair shafts penetrate into skin through the destroyed hair follicles in the intergluteal cleft.

• #64 Pilonidal Cyst (for Parents) | Nemours KidsHealth

  https://kidshealth.org/en/parents/pilonidal-cyst.html

  Doctors think that pilonidal cysts form when loose hair and dead skin cells get trapped under the skin. […] The immune system treats the hair and dead skin cells as foreign, and forms a cyst around them that fills with fluid.

• #65 Pilonidal Sinus – Clinical Features – Management – TeachMeSurgery

  https://teachmesurgery.com/general/anorectal/pilonidal-sinus/

  Pilonidal sinus disease is a disease of the inter-gluteal region, characterised by the formation of a sinus in the cleft of the buttocks. It most commonly affects males aged 16-30 years. The most widely accepted theory for pilonidal sinus disease development begins with a hair follicle in the intergluteal cleft becoming infected or inflamed. This inflammation obstructs the opening of the follicle, which extends inwards, forming a pit (a characteristic feature of pilonidal sinus disease). A foreign body-type reaction may then lead to formation of a cavity, connected to the surface of the skin by an epithelialised sinus tract. These fluid-filled cavities (cysts) will often discharge serous fluid and can periodically become acutely infected to form a pilonidal abscess. […] Pilonidal sinus disease occurs from the infection or inflammation of hair follicles in the cleft of the buttocks.

• #66 Pilonidal Cyst and Sinus: Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/788127-overview

  It has been postulated that hair penetrates into the subcutaneous tissues through dilated hair follicles, which is thought to occur particularly in late adolescence, though follicles are not found in the walls of cysts. Upon sitting or bending, hair follicles can break and open a pit. Debris may collect in this pit, followed by development of a sinus with a short tract, with a not clearly understood suction mechanism involving local anatomy, eventually leading to further penetration of the hair into the subcutaneous tissue. […] A foreign body-type reaction may then lead to formation of an abscess. If given the opportunity to drain spontaneously, this may act as a portal of further invasion and eventually formation of a foreign body granuloma. Infection may result in abscess formation. Increased sweat may also contribute to development of a cyst and sinus. […] In summary, 3 pieces are instrumental in this process: (1) the invader, hair; (2) the force, causing hair penetration; and (3) the vulnerability of the skin.

• #67 Pilonidal sinus pathology

  https://dermnetnz.org/topics/pilonidal-sinus-pathology

  Pilonidal sinus is a common condition typically affecting the region of the base of the spine or the intergluteal cleft. It is regarded by many authors within the follicular occlusion tetrad as the primary process appears to be follicular occlusion. […] Sections show a dense inflammatory reaction usually occupying the entire dermis with erosion and ulceration of the overlying epidermis. Free hair shafts are often seen coursing through the inflammatory focus. Surrounding the free hair shafts is a polymorphous infiltrate which may be rich in plasma cells and lymphocytes. Foreign body-type giant cells and neutrophilic abscesses are also commonly observed. […] Correlation with the clinical findings is helpful.

• #68 Pilonidal sinus pathology

  https://dermnetnz.org/topics/pilonidal-sinus-pathology

  Pilonidal sinus is a common condition typically affecting the region of the base of the spine or the intergluteal cleft. It is regarded by many authors within the follicular occlusion tetrad as the primary process appears to be follicular occlusion. […] Sections show a dense inflammatory reaction usually occupying the entire dermis with erosion and ulceration of the overlying epidermis. Free hair shafts are often seen coursing through the inflammatory focus. Surrounding the free hair shafts is a polymorphous infiltrate which may be rich in plasma cells and lymphocytes. Foreign body-type giant cells and neutrophilic abscesses are also commonly observed. […] Correlation with the clinical findings is helpful.

• #69 Pilonidal Disease

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3140333/

  Additionally, the depth of the natal cleft is a developmental factor. Akinci and colleagues studied 50 patients undergoing surgery for pilonidal disease and 51 healthy volunteers who had their natal clefts measured with a specially designed device. They observed significantly deeper natal clefts in patients with pilonidal disease. […] Although often described incorrectly as a cyst, pilonidal cavities are not true cysts and lack a fully epithelialized lining; however, the fibrous tracts of the sinus may be epithelialized. Pilonidal sinus or disease is therefore the correct term. The majority of sinus tracts extend cephalad; however, additional sinuses may branch laterally. […] Interestingly, hair follicles are rarely seen on pathologic examination. Cavities may contain hair, debris, and granulation tissue. The local cellular infiltration is sizable and often includes foreign body giant cells in association with hair.

• #70 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  Once one hair inserts successfully, other hairs can insert more easily. Foreign body tissue reaction and infection follow, and the primary sinus of pilonidal disease forms. […] Isolated reports of pilonidal sinus occurring in unusual locations, such as the umbilicus, a healed amputation stump, and interdigital clefts, and the recurrence of the disease in an adequately excised area support the acquired theory of this disease and Karydakiss concept of hair insertion.

• #71 Approach to Interdigital Pilonidal Sinus: Our Clinical Experience and Literature Review | ClinMed International Library | International Journal of Surgery Research and Practice

  https://clinmedjournals.org/articles/ijsrp/international-journal-of-surgery-research-and-practice-ijsrp-3-042.php?jid=ijsrp

  Interdigital pilonidal sinus disease, also called „barber’s disease,” is an acquired occupational disease. […] Although the etiology has not been fully clarified, the disease is thought to be mostly caused by the formation of an acute and chronic infection focus under the skin by hair shed from the skin. […] The histological structure of interdigital pilonidal sinus disease (IPSD) observed in barbers was defined as a foreign body granuloma for the first time in 1942 by Templeton. […] IPSD is now generally accepted as an acquired disease independent of body location. […] In addition, IPSD is known as an occupational disease among barbers because the sinuses develop a foreign body reaction against customers’ hair. […] The disease progresses with the formation of a sinus and eventually a cyst.

• #72 10 Pilonidal Disease | Abdominal Key

  https://abdominalkey.com/part-ii-anorectal-disease-5/

  Once one hair inserts successfully, other hairs can insert more easily. Foreign body tissue reaction and infection follow, and the primary sinus of pilonidal disease forms. […] Isolated reports of pilonidal sinus occurring in unusual locations, such as the umbilicus, a healed amputation stump, and interdigital clefts, and the recurrence of the disease in an adequately excised area support the acquired theory of this disease and Karydakiss concept of hair insertion.

• #73 Pilonidal sinus of eyelids: A rare presentation – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/pilonidal-sinus-of-eyelids-a-rare-presentation/

  Pilonidal sinus (PS), a term first used by Hodges in 1880, is a lesion that arises in the midline, in a skin dimple, in relation to the tip of the coccyx. […] Initially, congenital theories were suggested for pathogenesis of PS, but most recently acquired theory has been widely accepted by surgeons. […] Therefore, with current knowledge, we hypothesize that the routine procedure of plucking (threading) of eyebrows may have initiated the suction force, which is required for pathogenesis. The wrinkled skin present over eyelids could have contributed to the penetration of hair. Three pieces are instrumental in this process: (1) The invader, hair; (2) the force, causing hair penetration; and (3) the vulnerability of the skin. […] Kurokava et al conducted a study to elucidate the pathogenesis of PS by evaluating its cytokeratin (CK) expression and suggested PS to be part of follicular occlusion disease based on CK expression.

• #74 Pilonidal sinus of the cheek: an extremely rare clinical entity—case report and brief review of the literature | Journal of Medical Case Reports | Full Text

  https://jmedicalcasereports.biomedcentral.com/articles/10.1186/s13256-020-02561-z

  Pilonidal sinus (PNS) refers to a subcutaneous sinus which contains hair. It is an acquired condition caused by penetration of hair fragments into the skin. This hair containing cavity usually is asymptomatic and the only sign of its presence may be a small pit on the surface of the skin. Due to infection of its content, it may present clinically either as a recurrent discharging sinus or an abscess. […] The etiology of pilonidal sinus remains unclear. There are two main theories regarding its etiology acquired and congenital. In general, at least three conditions need to be fulfilled for a pilonidal sinus to occur: first is hair in the skin and, second, some kind of wrinkled skin, such as the natal cleft or a scar. The third condition is a mixture of hormonal and hygienic problem. […] For PNS of the cheek to occur, repeated mechanical trauma from shaving coupled with contributions from high testosterone level, repeated folliculitis and intrusion of hair fragment through the damaged overlying skin seems to play the major contributory role.

• #75 Pilonidal sinus of the cheek: an extremely rare clinical entity—case report and brief review of the literature | Journal of Medical Case Reports | Full Text

  https://jmedicalcasereports.biomedcentral.com/articles/10.1186/s13256-020-02561-z

  Majority of facial PNSs occur in males. Males have facial hair which needs repeated shaving this leads to abundance of rootless razor sharp short hairs which are implicated in the pathogenesis of facial PNS. […] An ingrown hair inciting repeated irritation of the skin thereby causing its intrusion was excluded as a differential diagnosis because of the presence of many hairs deep inside the excised cyst. […] The standard method of management of facial PNS is excision and primary closure which is usually performed under general or local anesthesia. This may differentiate facial PNS from PNS of other areas where many non-surgical modalities exists.

• #76 Pilonidal sinus of external auditory canal as unpredicted lesion: rarest case presentation and review of literatures | The Egyptian Journal of Otolaryngology | Full Text

  https://ejo.springeropen.com/articles/10.1186/s43163-023-00384-5

  Pilonidal sinus (PNS) is a developmental benign lesion, which is commonly presented in hair-bearing areas exposed to continuous pressure friction. […] From the pathogenesis point of view, this lesion occurred through the interaction of three main predisposing factors: first is the presence of optimum levels of the sex hormones required for sufficient maturation of body sex criteria, which leads to the second factor that enhancement of the hair growth as a part of the normal sex development. The third factor is a mechanical factor in form of the presence of frequent pressure friction at the zones of active hair growth. Therefore, the incidence of this lesion becomes higher at the puberty age group, among which there will be the highest activity of hair growth. In the presence of persistent pressure friction, the actively growing hair will be pushed and affected inward resulting in the formation of a hole or tunnel at the skin. This tunnel may be got filled with fluid or pus accumulation because of the lack of proper personal hygiene at these areas and superadded infection leading to abscess collection. The lumen of the sinus itself will provide a significant negative pressure that cause more hair nesting and furthermore tunnel dilation, which causes more drawing in more hair, therefore the cycle will be perpetuated.

• #77 Pilonidal sinus of external auditory canal as unpredicted lesion: rarest case presentation and review of literatures | The Egyptian Journal of Otolaryngology | Full Text

  https://ejo.springeropen.com/articles/10.1186/s43163-023-00384-5

  By the interpretation of our case criteria with the accredited characters of PNS as general, we can reach the fact that the pathogenesis of PNS is not depending upon the excessiveness of the hair growth activity as a part of secondary sex characters maturation at puberty age due to high levels of sex hormones excretion. In the same context, the long-standing local pressure frictions are not a significant etiological factor for the development of PNS. This can be proved by our reported case who was before puberty, and the lesion was manifested at a still yet non-haired region with no possible pressure friction effect. […] The only acceptable explanation for the pathogenesis of this lesion among this child via the possibility of the foreign hair impaction at the EAC as the result of the scalp hair loss either spontaneously or during hair combing or trimming, subsequently as the immune response to this foreign body effect, the inflammatory granulomatous lesion will occur. This could be the same explanation for the pathogenesis of PNS among the barbers as well as animal hair trimmers, who developed this lesion at interdigital regions as the result of the pushing and impaction of the trimmed hair inward as foreign bodies. This will enhance and induce the reactive inflammatory granulomatous lesion, and it will be manifested as PNS.

• #78

  https://medicaljournalssweden.se/actadv/article/view/6569

  Pilonidal sinus disease is a comorbid disorder and may be the reason for first contact with the healthcare system of patients with hidradenitis suppurativa. […] Pilonidal sinus disease was present in 32.6% (269/839) of the patients and was associated with an early debut of hidradenitis suppurativa, a higher Hurley stage, inflammatory phenotype and a greater number of fistulas and perianal involvement. […] Elapsed time between pilonidal sinus disease and diagnosis of hidradenitis suppurativa was associated with higher disease severity. […] Pilonidal sinus disease is a frequent comorbidity and risk marker for hidradenitis suppurativa disease severity. […] Pilonidal sinus disease could be a sentinel event to identify patients who would benefit from close treatment and follow-up.

• #79 Pilonidal Sinus – Clinical Features – Management – TeachMeSurgery

  https://teachmesurgery.com/general/anorectal/pilonidal-sinus/

  Pilonidal sinus disease is a disease of the inter-gluteal region, characterised by the formation of a sinus in the cleft of the buttocks. It most commonly affects males aged 16-30 years. The most widely accepted theory for pilonidal sinus disease development begins with a hair follicle in the intergluteal cleft becoming infected or inflamed. This inflammation obstructs the opening of the follicle, which extends inwards, forming a pit (a characteristic feature of pilonidal sinus disease). A foreign body-type reaction may then lead to formation of a cavity, connected to the surface of the skin by an epithelialised sinus tract. These fluid-filled cavities (cysts) will often discharge serous fluid and can periodically become acutely infected to form a pilonidal abscess. […] Pilonidal sinus disease occurs from the infection or inflammation of hair follicles in the cleft of the buttocks.

• #80 Common surgical procedures in pilonidal sinus disease: A meta-analysis, merged data analysis, and comprehensive study on recurrence | Scientific Reports

  https://www.nature.com/articles/s41598-018-20143-4

  We systematically searched available databases. […] The purpose of this meta-analysis and merged data analysis was therefore to obtain a comprehensive assessment of recurrence and to ascertain determinants of recurrence of PSD with respect to specific surgical procedures and follow-up time. […] We found that the recurrence in PSD varied depending on the surgical procedure and on the length of follow-up. […] This indicates that a thorough evaluation of a procedure in view of recurrence has to include the specific relation of recurrence to follow-up time and cannot just be based on comparisons at one single follow-up time. […] Recurrence in PSD is highly dependent on surgical procedure and by follow-up time; both must be considered when drawing conclusions regarding the efficacy of a procedure.

• #81 Common surgical procedures in pilonidal sinus disease: A meta-analysis, merged data analysis, and comprehensive study on recurrence | Scientific Reports

  https://www.nature.com/articles/s41598-018-20143-4

  The strength of our conclusions is substantially buttressed by the extensive analysis of a large database pertaining to particular therapeutic procedures. […] Our meta-analysis of the data identified a relationship between recurrence of PSD and follow-up times for each different therapeutic approach. […] Recurrence varies between surgical procedures by a factor of 2,1 at 60 months in RCTs and 21 in all studies. […] Thus, any report of a given surgical procedure without specified follow up may contain a10 fold higher or lower true recurrence as the postulated one. […] The highest incidence of recurrence identified in our data, 67.9%, occurred 240 months after primary midline closures; so, this method should be abandoned straight away, while other traditional approaches such as primary open treatment can be justified, also when considering the development of more complicated surgeries involving flap techniques.

• #82 Can Pilonidal Cyst Lead to Cancer: Pilonidal Cyst Specialist Explains

  https://www.clinicahealth.in/can-pilonidal-cyst-lead-to-cancer-pilonidal-cyst-specialist-explains/

  According to Dr Purnendu Bhowmik, a pilonidal cyst specialist, skin affected with pilonidal cyst has a high chance of catching inflammation in the long run. The prolonged inflammation due to pilonidal sinus is a significant risk factor for squamous cell carcinoma (a type of skin cancer). […] Doctors opine that the recurring problem of pilonidal sinus contributes to the development of skin cancer. […] The repeated skin inflammation leads to abnormal changes in its repair mechanism, causing the growth of cancerous cells. Typically, the development of cancer cells is slow in the affected area. However, in some cases, immediate treatment is required to get rid of both skin cancer and pilonidal sinus. […] Timely treatment is the best way to prevent pilonidal sinus from developing into cancer.

• #83

  https://medicaljournalssweden.se/actadv/article/view/6569

  Pilonidal sinus disease is a comorbid disorder and may be the reason for first contact with the healthcare system of patients with hidradenitis suppurativa. […] Pilonidal sinus disease was present in 32.6% (269/839) of the patients and was associated with an early debut of hidradenitis suppurativa, a higher Hurley stage, inflammatory phenotype and a greater number of fistulas and perianal involvement. […] Elapsed time between pilonidal sinus disease and diagnosis of hidradenitis suppurativa was associated with higher disease severity. […] Pilonidal sinus disease is a frequent comorbidity and risk marker for hidradenitis suppurativa disease severity. […] Pilonidal sinus disease could be a sentinel event to identify patients who would benefit from close treatment and follow-up.

• #84 Can Pilonidal Cyst Lead to Cancer: Pilonidal Cyst Specialist Explains

  https://www.clinicahealth.in/can-pilonidal-cyst-lead-to-cancer-pilonidal-cyst-specialist-explains/

  According to Dr Purnendu Bhowmik, a pilonidal cyst specialist, skin affected with pilonidal cyst has a high chance of catching inflammation in the long run. The prolonged inflammation due to pilonidal sinus is a significant risk factor for squamous cell carcinoma (a type of skin cancer). […] Doctors opine that the recurring problem of pilonidal sinus contributes to the development of skin cancer. […] The repeated skin inflammation leads to abnormal changes in its repair mechanism, causing the growth of cancerous cells. Typically, the development of cancer cells is slow in the affected area. However, in some cases, immediate treatment is required to get rid of both skin cancer and pilonidal sinus. […] Timely treatment is the best way to prevent pilonidal sinus from developing into cancer.

• #85 Rethinking the causes of pilonidal sinus disease: a matched cohort study | Scientific Reports

  https://www.nature.com/articles/s41598-021-85830-1

  Our understanding of pilonidal sinus disease (PSD) is based on a paper published 29 years ago by Karydakis. […] Thus sweating may have a protective effect in PSD rather than being a risk factor. […] However, the pathomechanism of PSD has never been fully clarified. […] For decades surgeons have assumed that maceration of the IGF is a risk factor for PSD and that pilonidal patients sweat more than people without the disease. Our analysis adjusting for confounding disproves this. […] Thus our findings overturn long-standing assumptions about the genesis of PSD. […] If the IGF were totally dry, no hair would be retained by adhesion. […] However, we did not see any of these effects in our German PSD cohort. […] Three different statistical techniques that adjust for confounding consistently demonstrated less sweating in PSD patients. […] Our findings present a different picture of pilonidal disease than the one provided by Karydakis. […] Future research into PSD should focus on skin texture changes, hormonal changes during puberty, age-related sweating, hair strength, and skin-to-hair-strength ratio changes.

• #86 Morphological features of pilonidal cysts of the sacro…

  https://ppch.pl/seo/article/228126/en

  Despite the fact that the pilonidal cyst of the sacrococcygeal region is a long-known disease, the mechanism of accumulation or absence of hair in the cyst remains unclear, which affects the accuracy of the name of the disease, as well as understanding of its pathogenesis. […] Aim to perform morphological examination of pilonidal cysts of the sacrococcygeal region, to determine the nature of the cysts, the frequency of hair in the cyst cavity and to determine the causes and mechanism of its accumulation in cysts. […] The mechanism of hair accumulation in the cavity of the pilonidal cyst has not been fully studied. There are various assumptions of researchers. We explain the accumulation of hair in the cyst cavity by the deepening, „falling” of still functioning hair follicles after inflammation by the mechanism of follicular occlusion to the subcutaneous tissue, which is a pliable and soft tissue where lipocytes and thin fibrous membranes between them are unable to resist unlike the strong dermis. Hair, which during growth is not able to reach the surface of the skin through the hair funnel, continues to grow from the deepened follicle and accumulates subcutaneously filling the cavity – the pilonidal cyst. […] All this indicates the growth of hair and their accumulation subcutaneously, as a result of inflammatory changes in the hair follicle and surrounding tissues, rather than getting from the outside.

• #87 Morphological features of pilonidal cysts of the sacro…

  https://ppch.pl/seo/article/228126/en

  Despite the fact that the pilonidal cyst of the sacrococcygeal region is a long-known disease, the mechanism of accumulation or absence of hair in the cyst remains unclear, which affects the accuracy of the name of the disease, as well as understanding of its pathogenesis. […] Aim to perform morphological examination of pilonidal cysts of the sacrococcygeal region, to determine the nature of the cysts, the frequency of hair in the cyst cavity and to determine the causes and mechanism of its accumulation in cysts. […] The mechanism of hair accumulation in the cavity of the pilonidal cyst has not been fully studied. There are various assumptions of researchers. We explain the accumulation of hair in the cyst cavity by the deepening, „falling” of still functioning hair follicles after inflammation by the mechanism of follicular occlusion to the subcutaneous tissue, which is a pliable and soft tissue where lipocytes and thin fibrous membranes between them are unable to resist unlike the strong dermis. Hair, which during growth is not able to reach the surface of the skin through the hair funnel, continues to grow from the deepened follicle and accumulates subcutaneously filling the cavity – the pilonidal cyst. […] All this indicates the growth of hair and their accumulation subcutaneously, as a result of inflammatory changes in the hair follicle and surrounding tissues, rather than getting from the outside.

• #88

  http://pat.zsmu.edu.ua/article/view/22589

  The occurrence of pilonidal cysts in Ukrainian population is up to 50 cases per 100.000. Nevertheless, the cause and the pathogenesis of pilonidal cyst to date remain unclear. […] Authors suggest the definite answer should be based primarily on the results of the morphologic evaluation of pilonidal cyst tissue. […] The absence of own epithelial elements in the pilonidal cysts and the secondary sinus tracts have been demonstrated. Hypertrophic growth of skin or hair follicle epithelium was evident in some specimens. Such changes seen in the deep layers of skin on the border with adipose tissue were similar to epidermal polyps. […] There are some morphological features suggesting the acquired origin of the pilonidal disease as follows: […] Pilonidal cyst doesnt have own epithelium, and the epithelial fragments that occur are the fragments of disorganized hair follicles.

• #89

  http://pat.zsmu.edu.ua/article/view/22589

  In the pilonidal cysts tissues immunopathological cell reactions of foreign body rejection are evident. Disorganization and lysis of hair shafts, vessel hyalinosis, fibrinoid degeneration and lymphoid cells infiltration are critical components of pilonidal cysts morphogenesis. […] The important role in the consistent development of pathogenetic mechanisms of sinus ducts formation in sacrococcygeal pilonidal disease is played by common pathological mechanisms of tubular sinus ducts formation with hypertrophic skin epithelium growth in the external sinus tract area and on the fundus of enlarged hair follicle with epithelial polyp formation. […] Pilonidal disease has an acquired origin and develops when the loose hair shafts penetrate into skin through the destroyed hair follicles in the intergluteal cleft.

• #90 Pilonidal Sinus Disease (Pilonidal Cyst) – Dermatology Advisor

  https://www.dermatologyadvisor.com/home/decision-support-in-medicine/dermatology/pilonidal-sinus-disease-pilonidal-cyst/

  It is only those men and women who have a predisposing morphologic shape and curvature of their buttocks and who routinely create rhythmical, shearing movements with their lower backs and buttocks in their occupation and normal daily activities who will develop PSD. […] It has been suggested that gravity and intergluteal motion together create a type of vacuum that directs loose hair into the funnel of the pilonidal sinus.

• #91 Rethinking the causes of pilonidal sinus disease: a matched cohort study | Scientific Reports

  https://www.nature.com/articles/s41598-021-85830-1

  Our understanding of pilonidal sinus disease (PSD) is based on a paper published 29 years ago by Karydakis. […] Thus sweating may have a protective effect in PSD rather than being a risk factor. […] However, the pathomechanism of PSD has never been fully clarified. […] For decades surgeons have assumed that maceration of the IGF is a risk factor for PSD and that pilonidal patients sweat more than people without the disease. Our analysis adjusting for confounding disproves this. […] Thus our findings overturn long-standing assumptions about the genesis of PSD. […] If the IGF were totally dry, no hair would be retained by adhesion. […] However, we did not see any of these effects in our German PSD cohort. […] Three different statistical techniques that adjust for confounding consistently demonstrated less sweating in PSD patients. […] Our findings present a different picture of pilonidal disease than the one provided by Karydakis. […] Future research into PSD should focus on skin texture changes, hormonal changes during puberty, age-related sweating, hair strength, and skin-to-hair-strength ratio changes.

• #92 Rethinking the causes of pilonidal sinus disease: a matched cohort study | Scientific Reports

  https://www.nature.com/articles/s41598-021-85830-1

  Our understanding of pilonidal sinus disease (PSD) is based on a paper published 29 years ago by Karydakis. […] Thus sweating may have a protective effect in PSD rather than being a risk factor. […] However, the pathomechanism of PSD has never been fully clarified. […] For decades surgeons have assumed that maceration of the IGF is a risk factor for PSD and that pilonidal patients sweat more than people without the disease. Our analysis adjusting for confounding disproves this. […] Thus our findings overturn long-standing assumptions about the genesis of PSD. […] If the IGF were totally dry, no hair would be retained by adhesion. […] However, we did not see any of these effects in our German PSD cohort. […] Three different statistical techniques that adjust for confounding consistently demonstrated less sweating in PSD patients. […] Our findings present a different picture of pilonidal disease than the one provided by Karydakis. […] Future research into PSD should focus on skin texture changes, hormonal changes during puberty, age-related sweating, hair strength, and skin-to-hair-strength ratio changes.

• #93 Pilonidal sinus | PPT

  https://www.slideshare.net/slideshow/pilonidal-sinus-47289096/47289096

  Pilonidal sinus is an infection of the skin and subcutaneous tissue near the upper part of the natal cleft. It is caused by hair penetrating and becoming trapped in the skin. […] In WW II Patey and Scarf hypothesised origin of pilonidal sinus acquired by penetration of hair into subcutaneous tissue. […] Pathogenesis Hair and inflammation inciting factors On sitting/bending natal cleft stretches- breakage of follicles- opening of a pore/pit- collection of debris – pilonidal sinus – abscess Proof?? Pilonidal tract extends cephalad. Cavity contains hair, debris or granulation tissue. […] Karydakis believed that hair insertion is the cause for pilonidal sinus. […] Understanding the pathophysiology is essential for developing a treatment plan.

• #94 Common surgical procedures in pilonidal sinus disease: A meta-analysis, merged data analysis, and comprehensive study on recurrence | Scientific Reports

  https://www.nature.com/articles/s41598-018-20143-4

  From our analysis of data from more than 80,000 patients over 18 decades, we found that the Karydakis and the Bascom cleft lift procedures show the lowest recurrence at any time of follow-up, followed by rhomboid flaps and other flaps. […] The data on laser treatment still remain weak; long term follow-up data and extensive cohorts have not yet been published. […] Our results presented here suggest that the variances in recurrence are understandable once the follow-up time is taken into account. […] This dependence, i.e. the steepness of increase of recurrence with longer follow-up times, is specific to a surgical procedure. […] The choice of surgical therapy influences recurrence by a factor of up to 21. […] Follow-up of PSD patients should always be planned long term, i.e., five or ten years if reliable conclusions are to be drawn regarding the efficacy of a new procedure or on the efficacy of your own results using an already known technique.

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