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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