Contact Dermatitis



Contact Dermatitis


George R. Collins, DO

Joseph Susa, DO

Clay J. Cockerell, MD










Allergic contact dermatitis with a well-demarcated erythematous plaque in an area of skin contact with offending allergen (an adhesive in this case) shows sparing where gauze prevented contact image.






Irritant contact dermatitis of the hand is a nonimmune-mediated injury resulting in well-demarcated erythematous, crusted plaques at points of contact with the inciting irritant glove material.


TERMINOLOGY


Abbreviations



  • Allergic contact dermatitis (ACD)


  • Irritant contact dermatitis (ICD)


Synonyms



  • Hand dermatitis, diaper rash, and chemical dermatitis refer to types of irritant contact dermatitis


  • Allergic contact dermatitis may be referred to as eczematous dermatitis by some clinicians


Definitions



  • Contact dermatitis is a generic term for acute or chronic inflammatory reactions to substances that come in contact with the skin



    • ACD



      • Inflammatory skin disorder initiated by contact with an allergen to which the person has already been sensitized


      • Caused by cutaneous type IV cell-mediated delayed hypersensitivity allergic reaction


    • ICD



      • Inflammatory skin condition produced in response to non-immune-mediated direct toxic effect of chemical or physical irritant substance damaging the skin barrier


      • Irritants cause damage in many ways such as removal of surface lipids, damage of cell membranes, denaturation of epidermal keratins, cytokine release, and direct cytotoxic effect


ETIOLOGY/PATHOGENESIS


Environmental Exposure



  • ACD



    • Depends on sensitization, usually requires at least 2 exposures to exogenous antigen, and occurs only in sensitized individuals


    • Depending on degree of sensitization, even small amounts of antigen can elicit a reaction and sensitization may occur after only 2 exposures


    • Common allergens include nickel, fragrances, cosmetics, urushiol found in Rhus and Toxicodendron spp. (poison ivy/oak/sumac), formaldehyde, topical antibiotics, latex, rubber, balsam of Peru


  • ICD



    • Acute form can occur upon even a single exposure to toxic agent with severe cases resulting in necrosis


    • Effects depend on concentration of toxic agent with strong chemicals causing immediate reactions


    • Commonly due to repeated or continuous exposures to alkaline soaps/detergents, organic solvents, and excess moisture (hand, diaper area, colostomy site)


    • Common irritants include acids, alkalis, cement, metal salts, phenols, kerosene, ethylene glycol, lime acids, plants, alcohol solvents, acetone, fiberglass


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Prevalence of contact dermatitis (irritant and allergic) in USA varies from 1.5-5.4%


    • ACD



      • Affects a limited number of sensitized people, yet it is common and accounts for up to 20% of all cases of dermatitis in children


      • Sensitization to nickel is the leading cause of allergic contact dermatitis worldwide


      • In USA, rhus dermatitis due to poison ivy/oak/ sumac causes more cases of allergic contact dermatitis than all other allergens combined


    • ICD



      • Increased susceptibility (thin stratum corneum) in 15% of people, but anyone can be affected


      • Most common job-related skin disease (80% of cases)



      • Common entity, but only rarely biopsied


  • Age



    • Allergic and irritant contact dermatitis affect any age


  • Gender



    • Allergic and irritant contact dermatitis show no overall significant gender predilection


Site



  • ACD



    • Localized to 1 region or generalized in random pattern or on exposed areas


    • Initially confined to area of allergen contact and may be linear


  • ICD



    • Acute forms may be localized or generalized depending on nature of contact with toxic agent; chronic form commonly affects hands


Presentation

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Contact Dermatitis

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