Differentials
Atopic dermatitis
SIGNS / SYMPTOMS
Lesions in atopic dermatitis are generally symmetrically distributed over the flexural areas such as the antecubital fossa or popliteal fossa, less likely to be vesicular, more chronic in nature with seasonal variation, and not as sharply delineated.
Family history in atopic patients is often positive for other atopic diseases such as hayfever, allergic rhinitis, food allergies, or atopic dermatitis.
INVESTIGATIONS
Patch testing may be positive if contact dermatitis and atopic dermatitis co-exist in the same patient.
Nummular eczema
SIGNS / SYMPTOMS
Lesions in nummular eczema are coin-shaped plaques, with pinpoint vesiculation, and symmetrically distributed, most commonly on the extensor lower extremities.
INVESTIGATIONS
Patch testing is negative in case of nummular eczema.
Dyshidrotic eczema
SIGNS / SYMPTOMS
Dyshidrotic eczema almost exclusively involves the palms and soles, with little to no involvement of the dorsal hands and feet.
INVESTIGATIONS
Patch testing is negative in cases of dyshidrotic eczema.
Inverse psoriasis
SIGNS / SYMPTOMS
Well-demarcated erythema in intertriginous areas.
INVESTIGATIONS
History and clinical appearance; skin biopsy when uncertain.
Palmoplantar psoriasis
SIGNS / SYMPTOMS
Plaques and pustules on the palms and soles.
INVESTIGATIONS
History and clinical appearance; skin biopsy when uncertain.
Scabies
SIGNS / SYMPTOMS
Burrows and typical distribution on hands, feet, waist, axilla, or groin.
INVESTIGATIONS
History and clinical appearance; skin scraping with mineral oil prep when uncertain.
Tinea pedis
SIGNS / SYMPTOMS
Usually occurs between toes, on the soles, and on the sides of the feet; whereas contact dermatitis is more common on the dorsum of the foot.
INVESTIGATIONS
History and clinical appearance; potassium hydroxide prep when uncertain.
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