Contact Dermatitis

An inflammatory skin disorder caused by exposure to external substances

Types

  • Irritant Contact Dermatitis (ICD)
    • Caused by direct chemical damage to the skin.
    • Common irritants: detergents, acids/alkalis, solvents, soaps, saliva, cosmetics.
    • Most common form of contact dermatitis.
  • Allergic Contact Dermatitis (ACD)
    • Type IV hypersensitivity reaction mediated by T-cells.
    • Requires prior sensitization.
    • Common allergens: nickel (jewelry), fragrances, rubber/latex, hair dyes (PPD), preservatives, plants (poison ivy).

Risk Factors

  • Frequent water and soap exposure (e.g., healthcare workers).
  • Atopic background.
  • Occupational exposure (mechanics, cleaners, construction workers).
  • Use of cosmetics/perfumes.
  • Metals/latex sensitivity.

Clinical presentation

  • Acute Stage
    • Erythema, edema, papules, vesicles → may ooze/crust.
    • Localized to contact areas with defined borders.
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  • Subacute/Chronic Stage
    • Lichenification, scaling, fissures, dry thickened skin.
    • Persistent pruritus.
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  • Distribution
    • Corresponds to exposure site (e.g., wrist with watch, ears with earrings).

Investigations

  • Clinical evaluation based on history & examination.
  • Patch test for suspected allergic contact dermatitis.
    • Decrescendo erythema → negative test result → Irritant CD
    • Crescendo ertyhema → positive test result → Allergic CD
  • Rule out fungal or other dermatoses if needed (KOH test).

Management

  1. Identify and avoid the triggering agent (most important).
  1. Topical Therapy
      • Topical corticosteroids (mild–potent depending on severity/site).
      • Emollients/Moisturizers for skin barrier repair.
      • Calcineurin inhibitors (tacrolimus/pimecrolimus) as alternatives to steroids.
  1. Systemic Therapy
      • Antihistamines for pruritus.
      • Short course of systemic corticosteroids in severe/widespread cases.
  1. Supportive Care
      • Avoid scratching, use protective gloves.
      • Gentle soap-free cleansers.

Complication

  • Secondary bacterial infection (impetigo)
  • Viral infections (eczema herpeticum)
  • Sleep disturbances due to itching
  • Lichenification due to chronic scratching