Contact dermatitis

Allergic contact dermatitis 

Updated: 02/11/2021

© Jun Wang, MD, PhD
General features
  • Poison ivy, nickel and rubber gloves common associated factors
  • Persistent or relapsing
  • May get bacterial superinfection (impetiginization)
  • Irritant contact dermatitis: Similar conditions caused by chemical-induced direct damage of the skin, NO prior sensitization
  • With chronic irritation (rubbing or scratching), neurodermatitis (lichen simplex chronicus) may occur
Pathogenesis
  • Direct contact of antigens topically
  • Delayed hypersensitivity reaction (Type IV)
Activation of Langerhans cells results in CD4+ T-cell sensitization
Activation of memory T cells upon re-exposure
T-cell mediated response to site of antigen encounter

Clinical features
  • Occurs at site of contact
  • Usually develop within a few days of exposure
  • Pruritic papules and vesicles on an erythematous base
  • Lichenified pruritic plaques may indicate a chronic form
Pathological findings
  • Extensive spongiosis
  • May have intraepidermal vesicles, papillary dermal edema or perivascular lymphocytic infiltrates in upper dermis, also numerous eosinophils
Diagnosis
  • History
  • PE findings
  • Patch test
  • Other lab tests or histological examinations
  • Lack of recurrence after empiric treatment and avoidance of specific allergens
Management
  • Topical corticosteroid
  • Identify and removal of allergens


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