Allergic Contact Dermatitis

Initial Evaluation

The presentation of allergic contact dermatitis may range from mild edema, erythema, or eczematous papules and plaques, to bright erythema with vesicles, bullae, and crusting; less erythema, and lichenification or fissuring may be noted in chronic cases. Patients almost always report associated pruritus. The area of inflammation may extend slightly beyond the area of contact with the allergen, but linear or geometric patterns of inflammation in the shapes of potential contactants are highly suggestive of an allergic contact dermatitis.

Morphology: Allergic contact dermatitis may range from mild reactions (erythema) to vesiculation or eczematous changes.

Exposure to airborne contactants may present in a diffuse eruption on the face, neck, V-neck chest.

Allergic contact dermatitis to rubber in swimming goggles.

Allergic contact dermatitis to metals (in earrings, belt buckle, bracelet, ring, eyeglasses).

Allergic contact dermatitis to urushiol (poison ivy, oak, sumac) is often suggested by linear streaks of skin inflammation, marking areas where the patient brushed up against leaves of the plant.

Allergic contact dermatitis to topical antibiotic applied to an ulcer.

Allergic contact dermatitis to an herbal medication applied with an adhesive patch (either the herbal medication or adhesive are potential allergens in this case).

Allergic contact dermatitis to cosmetics: Hair-dye, nail lacquer (typically presents on the eyelids due to transfer of allergen from touching the eyes).

Differential diagnosis

Atopic dermatitis: Pruritic, eczematous, or lichenified plaques.

Scabies: Intensely pruritic, eczematous or lichenified plaques.

Dermatophyte (tinea pedis): Erythema, hyperkeratosis, and vesiculation may mimic shoe dermatitis. Dermatophyte infection typically involves the interdigital web spaces, which are usually spared in shoe contact dermatitis.

Drug eruption: Generalized pruritic, erythematous macules and papules may be difficult to distinguish between a systemic contact dermatitis.