Differential diagnosis
Seborrheic dermatitis—white or yellow, greasy scales on an erythematous base with distribution on scalp, nasolabial folds and chest.
Atopic dermatitis—chronic history of pruritic papules or plaques with scale localized to flexural areas or may be generalized; lichenification may be seen.
Contact dermatitis—papules and vesicles that correspond to contact with allergen.
Polymorphous light eruption—clusters of erythematous, pruritic papules or vesicles occurring most frequently on the neck, anterior chest, arms, and forearms following sun exposure; most common among women in their twenties.
Lichen planus—pruritic, purple, polygonal papules (4 Ps) that may involve hair, nails, and mucous membranes in addition to the skin; more common among women, with onset between 30 to 60 years of age; may last months to years.
Psoriasis—well-demarcated papules and plaques on an erythematous base with thick, silvery scale; characteristically found on elbows, knees, scalp, nails, and genitalia.
Steroid myopathy—A side effect of systemic steroids, usually seen 4 to 6 weeks after beginning of treatment.
Dermatomyositis-like reaction—onset of similar skin findings with initiation of the following medications and improvement with discontinuation: penicillamine, nonsteroidal anti-inflammatory drugs, and carbamazepine.
Overlap syndrome—The term “overlap” denotes that certain signs are seen in both dermatomyositis and other connective tissue diseases such as scleroderma, rheumatoid arthritis, and lupus erythematosus. Scleroderma and dermatomyositis are the most commonly associated conditions and have been termed sclerodermatomyositis or mixed connective disease. In mixed connective tissue disease, features of SLE, scleroderma, and polymyositis are evident such as malar rash, alopecia, Raynaud’s phenomenon, waxy-appearing skin, and proximal muscle weakness.1,2