Materiały źródłowe

• #1 Contact Dermatitis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK459230/

  Contact dermatitis is an inflammatory eczematous skin disease. It is caused by chemicals or metal ions that exert toxic effects without inducing a T-cell response (contact irritants) or by small reactive chemicals that modify proteins and induce innate and adaptive immune responses (contact allergens). Contact dermatitis is divided into irritant contact dermatitis and allergic contact dermatitis. Irritant contact dermatitis is a nonspecific response of the skin to direct chemical damage that releases mediators of inflammation predominantly from epidermal cells while allergic contact dermatitis is a delayed (type 4) hypersensitivity reaction to exogenous contact antigens. Immunological responses are due to the interaction of cytokines and T cells. […] Contact dermatitis is an inflammatory eczematous skin disease. It is caused by chemicals or metal ions that exert toxic effects without inducing a T-cell response (contact irritants) or by small reactive chemicals that modify proteins and induce innate and adaptive immune responses (contact allergens).

• #1 Contact Dermatitis Overview

  https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/contact-dermatitis-overview

  Contact dermatitis (CD) is a common skin problem occurring in 15% to 20% of people. […] CD may be allergic (ACD) or irritant (ICD). […] Allergic CD, on the other hand, is seen in genetically predisposed and previously sensitized individuals who react to even low concentrations of the agent. […] The diagnosis is made from history (what your doctor learns from talking to you including your hobbies, your work exposures, cosmetic/fragrance/hair dye/nail polish exposures, exposure to jewelry and other metals), physical exam and testing. […] The patch test is used for the diagnosis of contact dermatitis. […] Identifying the trigger is essential for correct advice to be given. […] Avoidance is key to treating the rash. […] Topical steroids are anti-inflammatory medications. […] Topical calcineurin inhibitors (pimecrolimus, tacrolimus) are anti-inflammatory agents that may provide another option in patients with ACD or ICD. […] Systemic steroids can be given by mouth or injection and may be needed if the rash is severe, associated with swelling, or if the rash covers much of your body.

• #2 Irritant Contact Dermatitis: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/1604561-overview

  Irritant contact dermatitis (ICD) is a nonspecific, nonallergic response of the skin to direct chemical damage from a corrosive agent that releases mediators of inflammation predominantly from epidermal cells. […] ICD arises as a result of activated innate immunity without prior sensitization, which differentiates it from allergic contact dermatitis. Different clinical forms may arise. The three main pathophysiologic changes are skin barrier disruption, epidermal cellular changes, and cytokine release. […] The pathogenesis of ICD involves resident epidermal cells, dermal fibroblasts, endothelial cells, and various leukocytes interacting with each other under the control of a network of cytokines and lipid mediators. Keratinocytes play an important role in the initiation and perpetuation of skin inflammatory reactions through the release of and responses to cytokines.

• #3 Contact Dermatitis: Causes, Symptoms, and Treatment

  https://www.healthline.com/health/contact-dermatitis

  Contact dermatitis occurs when the skin comes into contact with irritants or allergens, such as skin care products. […] Allergic contact dermatitis occurs when your skin develops an allergic reaction after exposure to a foreign substance. This causes your body to release inflammatory chemicals that can make your skin feel itchy and irritated. […] Irritant contact dermatitis accounts for 8 out of 10 cases of contact dermatitis, according to the National Eczema Association (NEA). It happens when your skin comes in contact with a toxic material. […] Symptoms of allergic contact dermatitis typically take 1 to 3 days to appear. However, you need exposure to a certain allergen at least once before developing allergic contact dermatitis, which is when you become sensitized to it. […] Irritant contact dermatitis usually causes symptoms within minutes and doesn’t require prior exposure to manifest.

• #4

  https://link.springer.com/article/10.1007/s40521-014-0030-0

  Irritant contact dermatitis (ICD) is a commonly occurring non-specific cutaneous inflammatory response to topical chemical, physiologic, and biologic toxins. […] Irritant contact dermatitis (ICD) refers to skin inflammation that occurs as a result of exposure to exogenous caustic or irritating chemicals or physical agents that cause direct cytotoxic skin damage leading to skin barrier disruption, cellular changes, and release of pro-inflammatory mediators. […] Although the precise cellular mechanisms remain to be elucidated, increasing evidence suggests the pathogenesis of ICD involves three main steps: irritation and disruption of the skin barrier, stimulation of the epidermal cells, and cytokine release leading to inflammation and skin changes. […] Exposure to irritants leads to stratum corneum damage and subsequent skin barrier impairment.

• #5 Irritant contact dermatitis

  https://dermnetnz.org/topics/irritant-contact-dermatitis

  Irritant contact dermatitis is a form of skin inflammation caused by contact with substances and/or environmental factors that injure the skin, damaging the skin barrier. […] Irritant contact dermatitis develops when chemical or physical agents damage the skin surface faster than the skin can repair. Irritants remove oils and natural moisturising factor from the outer layer of the skin, allowing chemical irritants to penetrate the skin barrier and trigger inflammation. […] Factors influencing the development and severity of the dermatitis include: Concentration, amount, and properties of the irritant; Duration and frequency of exposure, for example short concentrated or repeated prolonged low exposure; Skin susceptibility such as pre-existing skin damage or atopic tendency; Mechanical trauma including hand scrubbing; Environmental factors such as temperature extremes or humidity.

• #6

  https://link.springer.com/article/10.1007/s40521-014-0030-0

  Trans-epidermal water loss (TEWL) is a reflection of the barrier function of the stratum corneum. […] This impaired skin barrier facilitates the entry of irritants and is one of the fundamental defects in ICD pathophysiology. […] In acute-phase reactions of ICD, irritants penetrate the stratum corneum and directly activate epidermal keratinocytes, the key regulators of cytokine release and T cell activation. […] A cascade of events is initiated by damaged keratinocytes leading to activation of the innate immune system and subsequent release of pro-inflammatory cytokines, such as interleukin (IL)-1, IL-1, IL-6, and tumor necrosis factor (TNF)-. […] Chronic-phase reactions occur due to repeated exposure to solvents and surfactants that gradually extract lipids and water-retaining substances from the stratum corneum.

• #7 Irritant Contact Dermatitis: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/1604561-overview

  A variety of environmental stimuli (eg, ultraviolet light, chemical agents) can induce epidermal keratinocytes to release the following cytokines: Inflammatory cytokines (interleukin [IL]-1, tumor necrosis factor [TBF]-), Chemotactic cytokines (IL-8, IL-10), Growth-promoting cytokines (IL-6, IL-7, IL-15, granulocyte-macrophage colony-stimulating factor [GM-CSF], transforming growth factor [TGF]-), Cytokines regulating humoral versus cellular immunity (IL-10, IL-12, IL-18). […] Skin irritation predisposes the skin to develop sensitization to topical agents. Skin irritation by both nonallergenic and allergenic compounds induces Langerhans cell migration and maturation.

• #8 Allergic Contact Dermatitis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK532866/

  Allergic contact dermatitis (ACD) is a type 4 or delayed-type hypersensitivity response (DTH) by an individuals immune system to a small molecule (less than 500 daltons), or hapten, that contacts a sensitized individuals skin. […] The initial or induction phase of ACD occurs when the hapten combines with a protein to form a complex that leads to the expansion of an allergen-specific T cell population; the name for this process is sensitization. During the elicitation phase, re-exposure to the antigen leads to the development of dermatitis. […] Allergic contact dermatitis is an inflammatory disease of the skin that is caused by a type 4 hypersensitivity reaction. It results from the contact of an offending chemical or antigen with the skin, and the subsequent T-cell mediated response. […] The pathophysiology of allergic contact dermatitis starts with the contact of the allergen to the skin. This allergen penetrates that stratum corneum of the skin and is taken up by Langerhans cells. The antigens subsequently undergo processing by these cells and get displayed on their surface. Langerhans cells then migrate towards regional lymph nodes. The antigens taken up by these cells come in contact with the adjacent T-lymphocytes. Due to the process of clonal expansion as well as cytokine-induced proliferation, antigen-specific T lymphocytes get created. These lymphocytes may then travel through the blood and into the epidermis. This process collectively is known as the sensitization phase of allergic contact dermatitis. The elicitation phase is what occurs after reexposure to the antigen takes place. The Langerhans cells containing the antigen interacts with the antigen-specific T-lymphocytes for that antigen, which triggers a cytokine-induced proliferation process. This proliferation, in turn, creates a localized inflammatory response.

• #9 Basic mechanisms and pathophysiology of allergic contact dermatitis – UpToDate

  https://www.uptodate.com/contents/basic-mechanisms-and-pathophysiology-of-allergic-contact-dermatitis

  Allergic contact dermatitis (ACD) is a common inflammatory skin disease presenting with pruritic, eczematous lesions. ACD results from a T cell-mediated, delayed type hypersensitivity reaction elicited by the contact of the skin with the offending chemical in individuals who have been previously sensitized to the same chemical. […] This topic will discuss the immune mechanisms and pathophysiology of ACD. […] Pathogenesis of contact allergic dermatitis.

• #10 Contact Dermatitis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK459230/

  Irritant contact dermatitis is due to sufficient inflammation arising from the release of proinflammatory cytokines from keratinocytes, usually in response to chemical stimuli. It mainly causes skin barrier disruption, epidermal cellular changes, and cytokine release. […] Allergic contact dermatitis is T-cell mediated inflammation of the skin caused by repeated skin exposure to haptens in a sensitized individual. […] Allergic contact dermatitis has two phases. The sensitization phase in which antigen-specific effector T cells are induced in the draining lymph nodes by antigen captured cutaneous dendritic cells that migrate from the skin. The elicitation phase includes effector T cells that are activated in the skin by antigen captured cutaneous dendritic cells and produce various chemical mediators, which create antigen-specific inflammation. […] Photo contact dermatitis occurs when an allergen becomes an irritant in the presence of light.

• #11

  https://link.springer.com/article/10.1007/s40521-022-00299-1

  The understanding of the cellular and molecular pathogenesis of allergic contact dermatitis (ACD) has increased dramatically. […] The understanding of the cellular and molecular pathogenesis of allergic contact dermatitis has improved considerably. […] The binding of haptens is the first step in the development of allergic contact dermatitis. […] Upon skin contact, professional antigen-presenting cells (APC) may be involved in the clinically imperceptible sensitisation phase. […] The presentation of antigen by matured DC to nave T cells is called immunological priming and, as far as known, irreversibly. […] The clinical manifestations of ACD are the result of a T-cell-mediated inflammatory response that occurs after re-exposure to the harmful hapten either in the skin or, upon systemic exposure, in a more generalised manner.

• #12 Allergic contact dermatitis – Wikipedia

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

  In contact allergies, the molecules responsible (allergens) are typically small and cannot be directly recognized by the immune system. These allergens can trigger a reaction only after they undergo a process called haptenization. During haptenization, the allergens bind to larger molecules (carrier proteins) naturally present in the skin. This complex of allergen and carrier protein is what the immune system detects as foreign, leading to an allergic response. […] The conjugate formed is then recognized as a foreign body by the Langerhans cells (LCs) (and in some cases other Dendritic cells (DCs)), which then internalize the protein; transport it via the lymphatic system to the regional lymph nodes; and present the antigen to T-lymphocytes. This process is controlled by cytokines and chemokines with tumor necrosis factor alpha (TNF-) and certain members of the interleukin family (1, 13 and 18) and their action serves either to promote or to inhibit the mobilization and migration of these LCs.

• #13 Allergic contact dermatitis – Wikipedia

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

  Once within the lymph glands, the differentiated DCs present the allergenic epitope associated with the allergen to T lymphocytes. These T cells then divide and differentiate, clonally multiplying so that if the allergen is experienced again by the individual, these T cells will respond more quickly and more aggressively. […] White et al. have suggested that there appears to be a threshold to the mechanisms of allergic sensitization by ACD-associated allergens (1986). This is thought to be linked to the level at which the toxin induces the up-regulation of the required mandatory cytokines and chemokines. It has also been proposed that the vehicle in which the allergen reaches the skin could take some responsibility in the sensitization of the epidermis by both assisting the percutaneous penetration and causing some form of trauma and mobilization of cytokines itself.

• #14 Allergic Contact Dermatitis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK532866/

  The intensity of the inflammatory response in allergic contact dermatitis is dependent on both the sensitizing ability of the allergen and the concentration of the allergen present. Poison ivy is an example of a strong sensitizer that can create an intense inflammatory response, even in small concentrations. […] The goal of the treatment of allergic contact dermatitis is to decrease the inflammatory response that is triggered by the type 4 hypersensitivity reaction. Reactions caused by strong sensitizers may require quicker and more aggressive treatment as the intensity of dermatitis will increase. Identifying and removing the allergen is the most effective definitive treatment.

• #15 Role of Innate Immunity in Allergic Contact Dermatitis: An Update

  https://www.mdpi.com/1422-0067/24/16/12975

  Our understanding of allergic contact dermatitis mechanisms has progressed over the past decade. Innate immune cells that are involved in the pathogenesis of allergic contact dermatitis include Langerhans cells, dermal dendritic cells, macrophages, mast cells, innate lymphoid cells (ILCs), neutrophils, eosinophils, and basophils. […] Here we discuss the updated pathogenesis of ACD and the recent findings focusing on the roles of the innate immune system in ACD during the sensitization and elicitation phases. […] ACD pathogenesis consists of the sensitization phase (in which the immune system is primed to the allergen) and the elicitation phase (the subsequent immunological response to the re-exposed allergen), and is known as type IV (delayed-type) hypersensitivity reaction. […] The sensitization phase is known as an afferent or induction phase, where a hapten makes contact with the skin locally (or systemically via the gut or airway).

• #16 Role of Innate Immunity in Allergic Contact Dermatitis: An Update

  https://www.mdpi.com/1422-0067/24/16/12975

  ICD initiates when irritants disrupt the skin barrier function and induce spongiosis (intercellular edema) and even necrosis, resulting in the production of damage-associated molecular patterns (DAMPs). Innate immune cells then recognize the DAMPs via pattern recognition receptors (PRRs) including toll-like receptors (TLRs) and produce various cytokines, chemokines, and neuropeptides including tumor necrosis factor (TNF)-α, interferon (IFN)-α, interleukin (IL)-1β, IL-6, IL-12, IL-18, IL-23, and substance P. […] Recent findings show innate immune cells are actively involved in ACD development not only in the sensitization phase but also in the elicitation phase. […] The elicitation phase is known as an efferent or challenge phase, where the hapten interfaces with the same region of skin after the sensitization phase is completed and leads to the clinical appearance of acute ACD (erythema; papulation; vesiculation) possibly within 24~72 h. […] Cytotoxic CD8+ T cells, considered as the primary and key hapten-specific effector T cells, are localized both in the epidermis and dermis and are responsible for histological changes (epidermal-dermal interface dermatitis with spongiosis and inflammatory cell infiltration mainly consisting of lymphocytes and neutrophils).

• #17 Allergic contact dermatitis: Immune system involvement and distinctive clinical cases | Allergologia et Immunopathologia

  https://www.elsevier.es/en-revista-allergologia-et-immunopathologia-105-articulo-allergic-contact-dermatitis-immune-system-S030105461100200X

  The inflammatory reaction, determined by type 1 or type 17 cytokines, persists for only a few days; its rate decreases through the clearance of hapten from the skin and the activation of regulatory T cells. […] Human hapten-specific CD8+ T cells show a type 1 cytokine profile, whereas the cytokine released by CD4+ T cells are more variable, with a predominance of Th1 cells and a lower number of Th2 cells. […] Increased IL-18 serum levels have been found in patients with allergic contact dermatitis. This pro-inflammatory cytokine is involved in the Th1 response and immune cell infiltration into the tissues, so it probably has a role in the induction of contact dermatitis, together with IL-12 and IFN-gamma.

• #18 Role of Innate Immunity in Allergic Contact Dermatitis: An Update

  https://www.mdpi.com/1422-0067/24/16/12975

  The NLRP3 inflammasome consists of NLRP3 (as a sensor molecule), the adaptor protein, and the cysteine protease pro-caspase 1. The key role of the NLRP3 inflammasome in ACD is the production of IL-1β and IL-18. […] Unfolded protein response (UPR) is a response associated with endoplasmic reticulum stress that maintains the homeostasis of the proteomes by regulating protein synthesis, translocation, post-translational modifications, folding, and the degradation of less toxic protein aggregates at steady state. […] Consequently, the roles of LCs in ACD include (1) activation, maturation, and migration into the draining lymph node in response to DAMPs via PRRs, and finally the presentation of haptens/antigens to naïve T cells, (2) induction of cytotoxic CD8+ T cells and effector CD4+ T cells including Th1, Th2, Th17, and Th22 cells, and (3) induction of regulatory T cells and T-cell anergy, thereby inducing tolerance. […] Overall, mast cells may play inhibitory roles in murine ACD models possibly via the maintenance of IL-10-producing regulatory B cells in the skin, although there are several controversial findings regarding IL-10 derived from mast cells.

• #19

  https://link.springer.com/article/10.1007/s40521-022-00299-1

  The hapten-triggered innate immune response results in the release of pro-inflammatory mediators. […] The infiltrated lymphocytes produce inflammatory cytokines such as INF-, IL-4, IL-17 and TNF-. […] In the early phase of ACD, tissue damage is mainly due to apoptosis of keratinocytes carrying the hapten protein complex on MHC class I molecules, triggered by CD8+ T cells, via the perforin/granzyme or Fas/FasL pathways. […] The inflammatory response lasts for several days and then subsides after activation of downregulatory mechanisms. […] Regulatory T cells (Tregs) may play a role in the sensitisation and elicitation phases of ACD.

• #20 Contact Dermatitis – Dermatologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/dermatologic-disorders/dermatitis/contact-dermatitis

  Multiple allergens can cause ACD. […] Nickel sulfate is the most common contact allergen in most populations. […] The Toxicodendron species of plant (eg, poison ivy, poison oak, poison sumac) accounts for a large percentage of ACD, including moderate and severe cases. […] Photoallergic contact dermatitis is a variant of ACD, in which a substance becomes sensitizing only after it undergoes structural change triggered by ultraviolet light.

• #21 Allergic Contact Dermatitis: Symptoms, Causes, and Treatment – DermNet

  https://dermnetnz.org/topics/allergic-contact-dermatitis

  Allergic contact dermatitis is a type 4 or delayed hypersensitivity reaction and occurs 4872 hours after exposure to the allergen. The mechanism involves CD4+ T-lymphocytes, which recognise an antigen on the skin surface, releasing cytokines that activate the immune system and cause the dermatitis. […] Patients with atopic dermatitis associated with defective filaggrin (a structural protein in the stratum corneum) have a high risk of also developing allergic contact dermatitis. […] Allergic contact dermatitis starts as a localised reaction to an allergen in contact with the skin, but severe reactions may generalise due to autoeczematisation and can lead to erythroderma. […] Sometimes contact allergy arises only after the skin has been exposed to ultraviolet light. The rash is confined to sun-exposed areas even though the allergen may have been in contact with covered areas. This is called photocontact dermatitis.

• #22 Contact dermatitis: Triggers and treatment

  https://www.medicalnewstoday.com/articles/318099

  Photocontact dermatitis requires the presence of an irritant and exposure to sunlight. […] Contact dermatitis causes inflammation of the skin. It results from contact with an irritating substance and can lead to an itchy rash or even blisters. […] A person may also experience contact dermatitis due to an allergic reaction to a substance, such as a preservative in skin care products or a certain plant. Chemicals and other corrosive agents may also cause contact dermatitis. […] In rare cases, a combination of an irritant and sunlight exposure may cause a rash. Medical professionals refer to this as photocontact dermatitis.

• #23 Systemic contact dermatitis – Indian Journal of Dermatology, Venereology and LeprologyViber icon

  https://ijdvl.com/systemic-contact-dermatitis/

  Systemic contact dermatitis (SCD), better termed systemically reactivated allergic contact dermatitis, is a type of contact hypersensitivity reaction in which ingestion or other systemic exposure to a contact allergen occurs in an already sensitized person. […] Although the initial sensitizing exposure is usually by topical application, re-exposure by the oral, intravenous or inhalation routes can cause SCD. […] These reactions may occur not only after ingestion of the primary allergen, but also after ingestion of other immunochemically related allergens. […] Probably all allergens have the capacity to elicit SCD in the presence of sufficiently strong pre-existing sensitivity and a large enough administered dose. […] However, clinically significant SCD occurs only to certain allergens to which we are frequently exposed through a variety of routes.

• #24 Systemic contact dermatitis – Indian Journal of Dermatology, Venereology and LeprologyViber icon

  https://ijdvl.com/systemic-contact-dermatitis/

  Mechanism of systemic contact dermatitis […] Sensitized individuals may develop skin eruptions within hours of systemic allergen exposure. […] This suggests that mechanisms other than type IV delayed-type hypersensitivity are involved. […] There is evidence that systemic reactions to ingested haptens can be mediated by a type III immunologic reaction. […] Urticaria and anaphylaxis-type reactions, e.g., those occurring in latex-sensitive patients upon eating bananas, tomatoes, etc., involve IgE-mediated type I reactions.

• #25 Airborne Contact Dermatitis

  https://www.opendermatologyjournal.com/VOLUME/14/PAGE/31/FULLTEXT/

  Airborne contact dermatitis is an inflammatory reaction linked to various contactants suspended in the air. The diagnosis of this complaint is based on the patient history and on follow-up, observation of the presence of dust or of volatile causative agents, on the distribution of the lesions, and on the results of patch tests. […] The common belief is that occupational forms are more frequent than non-occupational, in the same way as airborne irritant contact dermatitis is thought to be more common than the allergic form of airborne contact dermatitis. […] The skin symptoms of airborne contact dermatitis do not generally have any special or peculiar morphologic characteristics and can, thus, be confused with those of common contact dermatitis of the corresponding category. […] The most common sites for airborne contact dermatitis are the parts of the body that are exposed to the air: the face, neck, upper aspect of the chest (V region of the neck), hands, wrists, underarms, and sometimes, lower legs in women.

• #26 Airborne Contact Dermatitis

  https://www.opendermatologyjournal.com/VOLUME/14/PAGE/31/FULLTEXT/

  The upper eyelids are particularly susceptible to airborne irritants or allergens, which can easily become trapped and, therefore, accumulate in this area. […] Apart from classic eczematous lesions (acute, subacute, or chronic), airborne contact dermatitis can manifest with peculiar papular-follicular pictures (fiberglass dermatitis) or as multiforme-like erythema (wood dust and the fumes of plants in combustion). […] Airborne contact dermatitis is a morphological diagnosis that encompasses all acute or chronic dermatoses predominantly of exposed parts of the body, which are caused by substances which, when released into the air, settle on the exposed skin. […] Contact dermatitis is designated as airborne based on the history of the patient and the follow-up, existence of dust or of volatile causative agents, the morphology and distribution of the lesions, and the results of epicutaneous tests.

• #27 Contact Dermatitis: Causes and Risk Factors

  https://www.verywellhealth.com/contact-dermatitis-causes-83205

  Contact dermatitis is an itchy, blistering skin rash typically caused by skin’s direct contact with a substance. In the irritant type of contact dermatitis, the most frequent triggers are chemicals such as in soaps, bleach, dyes, and solvents. In allergic contact dermatitis, common allergens include nickel, adhesives, plants, cosmetics, and topical medications. […] The chemicals released from the plants, called urushiols, are what cause dermatitis. Urushiol can be carried on the fur of animals, garden tools, sports equipment, and clothing. […] Systemic (or whole-body) contact dermatitis can occur as a result of medications, chemicals, and foods. In these cases, a person first has a sensitization due to contact with the skin and then may react to the same or similar compounds in food, drink, or medications taken orally, inhaled, or through other non-skin routes. […] There appears to be some genetic predisposition to contact dermatitis, as some people are more prone to develop allergies to chemicals, while others with the same exposure do not. […] While some genes have been proposed as increasing your risk, there are no definitive culprits.

• #28 Allergic Contact Dermatitis > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/dermatitis

  There arent different kinds of allergic contact dermatitis, but there are many different allergens that can cause the condition. […] Allergic contact dermatitis needs to be distinguished from irritant contact dermatitis, rashes that are usually caused by repeated exposure to soaps, detergents or industrial chemicals. […] Typically a diagnosis of allergic contact dermatitis is made by a dermatologist. […] Patch testing involves the application of square patches that are impregnated with a variety of different allergens typically 36 of the most common ones. […] Allergic contact dermatitis is best treated by identifying and avoiding the allergen(s) that you are sensitized to. […] A persons ability to develop an allergic response is thought to be determined by genetic factors and the frequency and intensity of exposure to the allergen. […] The integrity of the skin barrier is considered to be an important element in the sensitization process. […] According to Dr. Choate, one thing that sets Yale Medicine dermatologists apart is their willingness to aggressively pursue results.

• #29 Contact Dermatitis – Fonacier L, Feldman E (Updated 2020)

  https://www.worldallergy.org/component/content/article/contact-dermatitis-fonacier-l-feldman-e?catid=16&Itemid=101

  Simultaneous exposure to both irritant and contact allergens may produce additive, synergistic or antagonistic responses. […] If present at higher concentrations, allergens involved in ACD have the potential of establishing an ICD by up-regulating pro-inflammatory cytokines and/or enhancing the dermal penetration of the allergen.

• #30 Irritant contact dermatitis

  https://dermnetnz.org/topics/irritant-contact-dermatitis

  Irritant dermatitis is often the result of the cumulative impact of multiple irritants. […] Irritant contact dermatitis may be diagnosed on detailed medical history, including occupational exposures, and clinical examination. There is no test for irritant contact dermatitis. Patch testing may be necessary to distinguish it from allergic contact dermatitis. Irritant and allergic contact dermatitis can co-exist. […] Chronic irritant contact dermatitis can be slow to improve or resolve, especially of the hands, without obsessive care.

• #31 Eczema types: Contact dermatitis causes

  https://www.aad.org/public/diseases/eczema/types/contact-dermatitis/causes

  If you have a skin condition that lessens your skin’s ability to protect you from germs and other invaders, you have a greater risk. […] In the United States, contact dermatitis is one of the most common diseases caused by the workplace. […] If you can figure out what’s irritating your skin or causing an allergic reaction, you can get rid of the contact dermatitis. To heal your skin, you need to avoid what’s causing your skin to react.

• #32 Contact Dermatitis Symptoms, Causes & Treatment | Spire Healthcare

  https://www.spirehealthcare.com/conditions/contact-dermatitis/

  Contact dermatitis is an inflammatory skin condition where your skin reacts to contact with a chemical or something you’re allergic to. […] Contact dermatitis is caused by allergens or irritants that cause your skin to become inflamed inflammation is your skin’s reaction to try to protect itself against the allergen or irritant. […] Allergic contact dermatitis is caused by contact with something you’ve previously become allergic to, sometimes without realising it. […] Irritant contact dermatitis is caused by frequently allowing your bare skin to come into contact with a substance that damages it. […] The symptoms can be made worse by heat, cold or humidity. […] You are more likely to develop irritant contact dermatitis if you work in certain occupations, such as agricultural workers, beauticians, caterers, chemical workers, cleaners, construction workers, cooks, electronics, hairdressers, healthcare workers, machine operators, mechanics, metalwork and vehicle assembly. […] It’s important to get a proper diagnosis so you can get the right treatment and prevent your contact dermatitis from becoming a chronic (long-term) condition, which may be harder to treat.

• #33

  https://www.nhs.uk/conditions/contact-dermatitis/causes/

  Contact dermatitis occurs when your skin reacts to a particular substance. […] Irritant contact dermatitis may be caused by frequent exposure to a weak irritant, such as soap or detergent. […] You’re at an increased risk of irritant contact dermatitis if you also have atopic eczema, which is the most common form of eczema. […] If you already have irritant contact dermatitis symptoms, they can be made worse by heat, cold, friction (rubbing against the irritant) and low humidity (dry air). […] If you develop the condition because of a substance you work with, it may be referred to as occupational irritant dermatitis. […] The first time you come into contact with an allergen, your body becomes sensitised to it, but does not react to it. It’s only when you’re exposed to the substance again that your immune system reacts and causes the skin to become red and itchy.

• #34 Contact dermatitis – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/contact-dermatitis/symptoms-causes/syc-20352742

  Contact dermatitis is caused by exposure to a substance that irritates your skin or triggers an allergic reaction. The substance could be one of thousands of known allergens and irritants. Often people have irritant and allergic reactions at the same time. […] Irritant contact dermatitis is the most common type. This nonallergic skin reaction occurs when an irritant damages your skin’s outer protective layer. […] Allergic contact dermatitis occurs when a substance to which you’re sensitive (allergen) triggers an immune reaction in your skin. It often affects only the area that came into contact with the allergen. But it may be triggered by something that enters your body through foods, flavorings, medicine, or medical or dental procedures (systemic contact dermatitis). […] People often become sensitized to allergens after many contacts with it over years. Once you develop an allergy to a substance, even a small amount of it can cause a reaction.

• #35 Contact Dermatitis: Rash Symptoms, Causes & Treatment | Ada

  https://ada.com/conditions/contact-dermatitis/

  Contact dermatitis is an inflammation of the skin triggered by a substance the skin has come into contact with. The substance may be an allergen, something that provokes an allergic reaction, or an irritant, something that damages the skin. Inflammation commonly results in red, itchy and cracked skin. […] There are two types of contact dermatitis: irritant contact dermatitis and allergic contact dermatitis. Of these, irritant contact dermatitis is the more common, accounting for roughly 80 percent of all cases. […] Irritant contact dermatitis occurs when the skin comes into contact with a substance that irritates the skin. Allergic contact dermatitis occurs when the skin comes into contact with a specific substance which triggers an allergic reaction, known as an allergen. […] A wide array of substances can cause an allergic reaction, though some of the most common include: Nickel, a substance common in metal alloys used in everyday items, such as jewellery, clothes and bra straps; Cobalt, a metal sometimes found in jewellery; Chromate, a metal sometimes found in cement mixtures; Cosmetics, such as perfumes, hair dyes and nail varnish. […] Treating contact dermatitis will typically involve moisturizers, topical corticosteroids and/or steroid tablets. […] Avoiding contact with the irritant or allergen that is causing contact dermatitis is the most effective way of preventing the condition.

• #36 Contact Dermatitis | Children’s Hospital of Philadelphia

  https://www.chop.edu/conditions-diseases/contact-dermatitis-children

  Contact dermatitis is a physiological reaction that occurs after skin comes in contact with certain substances. Irritants to the skin cause the vast majority of these reactions. The remaining reactions are caused by allergens, which trigger an allergic response. […] Plants, as well as metals, cosmetics, and medications, may also cause contact dermatitis: […] Many types of cosmetics can cause allergic contact dermatitis. Permanent hair dye that contains paraphenylenediamine is the most common cause. Other products that may cause problems include dyes used in clothing, perfumes, eye shadow, nail polish, lipstick, and some sunscreens. […] Neomycin, which is found in antibiotic creams, is a common cause of medication contact dermatitis. Local anesthetics may also cause contact dermatitis.

• #37 Contact dermatitis – treatments, symptoms and prevention | healthdirect

  https://www.healthdirect.gov.au/contact-dermatitis

  Contact dermatitis is a common red and itchy rash that happens when your skin touches an irritant or allergen. […] Contact dermatitis is caused by either allergens (such as plants or rubber) or irritants (such as certain soaps, chemicals or even water). […] Your doctor may diagnose allergic contact dermatitis with patch testing on your skin. […] Irritant contact dermatitis happens when your skin reacts to something that damages it. If your skin is long or often exposed to an irritant, it can no longer protect itself. This can lead to irritant contact dermatitis. […] Allergic contact dermatitis may be caused by: some medicines you put on your skin, cosmetics, hair dyes, plastic chemicals, rubber and glues, plants. […] Irritant contact dermatitis may be caused by: water (from washing your hands too many times), handwash, soaps, detergents or bleach, something acidic, such as lemon juice, industrial chemicals, nail polish remover.

• #38 Pathogenesis and diagnosis of contact dermatitis: Applications of reflectance confocal microscopy

  https://www.wjgnet.com/2218-6190/full/v3/i3/45.htm

  Contact dermatitis is the most common professional skin disease, with frequencies ranging from 24 to 170 every 100000 people. Approximately 20% of the United States population suffers from CD, causing loss of over four million work days and costing approximately $400 million per year. CD is classified into irritant (ICD) and allergic (ACD), with both subtypes displaying sub-acute, acute and/or chronic eczema. Despite their different origin, ICD and ACD often present similar clinical and histologic findings. Interestingly, the physiopathology of ICD and ACD is different, particularly during the initial phases of the inflammatory process. ACD requires pre-sensitization to haptens, i.e., low molecular weight antigens. This means that ACD actually is a delayed-type hypersensitivity inflammatory reaction mediated by memory T cells. Conversely, ICD is a non-specific inflammatory dermatosis caused by direct toxicity of the chemical inducer on skin cells. Cell damage produces inflammatory mediators that activate the innate arm of the immune system.

• #39 Pathogenesis and diagnosis of contact dermatitis: Applications of reflectance confocal microscopy

  https://www.wjgnet.com/2218-6190/full/v3/i3/45.htm

  The gold standard in CD diagnosis is patch-testing, although its validity and reproducibility are under question. RCM is a non-invasive technique that enables detailed study of CD over time. Several studies have correlated the CD findings obtained using RCM to those using conventional histology. RCM is therefore a promising tool to study CD since it enables following the temporal evolution of the disease at a cellular and even subcellular level, unlike conventional histology. […] ACD is, at its etiological core, a memory T cell-mediated, delayed-type hypersensitivity reaction to haptens that enter into contact with the skin. Sensitization is initiated by professional antigen-presenting cells in the skin, e.g., Langerhans cells (LC) and/or skin dendritic cells (sDC), which process the haptens and migrate to the lymph nodes, where they initiate the adaptive immune response. This causes amplification of memory T cells. Keratinocytes also contribute to the inflammatory reaction: some haptens, e.g., nickel, induce them to produce IL-23, which promotes the clonal expansion of TH17 T lymphocytes. ACD clinical manifestations appear in response to the activation of CD8+ and IFN-gamma-producing TH1 CD4+ T cells that mediate the elimination of the hapten-carrying keratinocytes.

• #40 Pathogenesis and diagnosis of contact dermatitis: Applications of reflectance confocal microscopy

  https://www.wjgnet.com/2218-6190/full/v3/i3/45.htm

  ICD is currently described as an inflammation not mediated by the immune system. However, eczema is caused by the activation of the innate arm of the immune system. Most chemical substances, depending on their concentration, can cause ICD. Penetration through the skin layers induces expression of cytokines and chemokines that cause the inflammatory reaction. Keratinocytes represent 95% of skin cells and they produce a plethora of inflammatory mediators upon chemical challenge. The best described in ICD are: IL-1 and , IL-6, IL-8, TNF-, GM-CSF and IL-10. […] RCM findings reveal additional differences between ACD and ICD. ICD displays a significant increase in the disruption of the stratum corneum as well as parakeratosis and increased epidermal thickening compared to ACD. On the contrary, ACD exhibits increased exocytosis and microvesicle formation, reaching a maximum difference at 96 h compared to ICD. Initial stages of ACD also exhibit blood vessel dilation in the deeper layers of the skin.

• #41 Pathogenesis and diagnosis of contact dermatitis: Applications of reflectance confocal microscopy

  https://www.wjgnet.com/2218-6190/full/v3/i3/45.htm

  RCM permits the evaluation of the changes that occur during ICD and ACD over time to establish a chain of events. Disruption of the stratum corneum is commonly observed during the first few hours after contact with the irritant substance. These changes are frequently absent in ACD at the same temporal point, but can appear later in sub-acute eczema produced during the development of ACD. The levels of exocytosis and spongiosis at the initial stages are similar in ICD and ACD, but latter stages reveal increased spongiosis in ACD, which is likely due to slower recovery compared to ICD. […] In summary, RCM is a very promising tool for the diagnosis and management of ACD and ICD, providing significant advantage over conventional histology (due to the possibility to manage the disease through repetitive assessment) and patch-testing, due to increased sensitivity and specificity. Furthermore, RCM can be used to evaluate the response to therapy and evolution of the disease over time.

• #42 Contact Dermatitis Treatment, Symptoms & Causes

  https://www.emedicinehealth.com/contact_dermatitis/article_em.htm

  Irritant contact dermatitis results from coming in contact with a substance that is directly toxic to your skin. […] The longer the substance remains on the skin, the more severe the reaction. […] Many chemicals, including industrial cleaning products and solvents, can cause this condition. […] The practice of ear piercing is known to predispose to nickel allergy. […] The use of topical antibiotics like neomycin is associated with an allergy to this antibiotic. […] Distinguishing allergic contact dermatitis from irritant contact dermatitis and other forms of dermatitis can be challenging. […] A red rash is the usual reaction. […] Your skin may develop small fluid filled structures (vesicles) that can cause weeping, a characteristic of these sorts of eruptions. […] This condition is distinguished from hives (urticaria) that produce short-lived itchy welts (wheals).

• #43 Canine allergic dermatitis: Pathogenesis, clinical signs, and diagnosis

  https://www.dvm360.com/view/canine-allergic-dermatitis-pathogenesis-clinical-signs-and-diagnosis

  Atopic dermatitis is a hypersensitivity reaction to inhaled or dermally absorbed environmental allergens and is a common cause of allergic skin disease of small animals. The development of atopic dermatitis is complex. In dogs, it is a genetically programmed and heritable disease. In cats, evidence suggests that the disease is heritable. Canine atopy can develop in any dog, but certain breeds are predisposed, such as terriers and retrievers. The immunologic mechanisms involved in the development of atopic dermatitis are the focus of a great deal of study. Part of the immune response involves an IgE-mediated type 1 hypersensitivity reaction, and it is hypothesized that the pathogenesis also involves a T cell-mediated reaction. For many years, it was presumed that allergen exposure and sensitization occurred primarily through inhalation, hence the name allergic inhalant dermatitis. Percutaneous allergen exposure is now thought to be an important additional part of the pathogenesis; it leads to a cytokine imbalance and altered T cell-mediated response. Allergens from epidermal exposure become bound to epidermal Langerhans’ cells and are presented to T cells. Th2 cells are then preferentially activated and secrete cytokines, triggering allergen-specific IgE antibody production. When allergens cross-link surface-bound IgE antibodies, mast cells degranulate, and preformed and synthesized inflammatory mediators (e.g., histamine, leukotrienes, and substance P) are released. It is this cascade of reactions that is involved in the production of pruritus and subsequent development of inflammation.

• #44 Allergic or Irritative Contact Dermatitis: Everything You Need to Know

  https://www.dexeryl.com/en/your-skin/atopic-dermatitis/different-types-of-eczema/allergic-contact-eczema

  In allergic contact dermatitis, lesions develop 1 to 3 days after exposure to the allergen, in case of repeated exposure. […] Allergic contact dermatitis heals slower than the irritative form. […] Patch tests are used to confirm the diagnosis by identifying the responsible allergens. The doctor applies small amounts of potential allergens on the skin, usually on the back. They then examine the skin’s allergic reaction to these substances after 48 hours to detect delayed allergic reactions. […] The first step in treating contact dermatitis is avoiding the responsible substances, which may involve various adaptations (skincare products, professional practices, hobbies, and home environment). […] Topical treatments for dermatitis rely on corticosteroids, to reduce inflammation and itching.

• #45 Contact Dermatitis – Skin Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/skin-disorders/itching-and-dermatitis/contact-dermatitis

  Treatment of contact dermatitis is not effective until there is no further contact with the substance causing the problem. […] Once the substance is removed, the redness usually disappears with time. […] Allergic contact dermatitis may take several weeks to resolve after people are no longer exposed to the allergen. […] Irritant contact dermatitis usually resolves faster.

• #46 Contact dermatitis – treatments, symptoms and prevention | healthdirect

  https://www.healthdirect.gov.au/contact-dermatitis

  Your doctor can diagnose allergic contact dermatitis by using patch testing. […] There is no specific test to diagnose irritant contact dermatitis. Your doctor may diagnose it based on your symptoms and history of exposure to irritants. […] Treatment for contact dermatitis involves finding the allergen or irritant and avoiding it. Your rash should slowly go away once you avoid the trigger. […] It’s possible to have different types of contact dermatitis at the same time. You may need to avoid several different allergens or irritants. […] If you have allergic or irritant contact dermatitis, your skin can become infected.

• #47 Role of Innate Immunity in Allergic Contact Dermatitis: An Update

  https://www.mdpi.com/1422-0067/24/16/12975

  Innate immune cells include Langerhans cells, dermal dendritic cells, monocytes, macrophages, mast cells, innate lymphoid cells (group 1 (natural killer cells; ILC1); group 2 (ILC2); group 3 (lymphoid tissue inducer cells; ILC3)), neutrophils, eosinophils, and basophils. These cells play more active roles in ACD than previously thought by using PRRs including TLRs and NLRs. […] We discussed the recent findings focusing on the roles of the innate immune system in ACD during the sensitization phase and elicitation phase.

• #48 Contact dermatitis | Nature Reviews Disease Primers

  https://www.nature.com/articles/s41572-021-00271-4

  The impact of dupilumab on patch testing and the prevalence of comorbid allergic contact dermatitis in recalcitrant atopic dermatitis: a retrospective chart review. […] For many years, allergen avoidance, topical corticosteroids, phototherapy and traditional, systemic immunosuppressants have been the mainstay for the treatment of CD; targeted therapies represent a new and exciting approach to benefit patients with recalcitrant disease.

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