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A Photo Quiz to Hone Dermatologic Skills

By DAVID L. KAPLAN, MD-Series Editor

annular lesionsCase 1:

For several weeks, this 21/2-year-old boy has had erythematous annular lesions on the lower trunk and proximal lower extremities. He was treated for pityriasis rosea only to have the lesions recur when the topical corticosteroid was discontinued.

Your diagnosis is . . .

A. Contact dermatitis.

B. Atopic dermatitis.

C. Extensive tinea corporis.

D. Pityriasis rosea.

E. Viral exanthem.

 

Case 2:

rash on footA 16-year-old boy with atopy has been bothered for a few months by an intermittent rash on the distal dorsal aspects of both feet. He also complains of having sweaty feet.

What are we looking at here?

A. Tinea pedis.

B. Candidiasis.

C. Contact shoe dermatitis.

D. Juvenile plantar dermatosis.

E. Hyperhidrosis.

 

Answers on next page

Case 1: B, Atopic dermatitis

This patient had nummular eczema attributable to his underlying atopic dermatitis. A new soap, moisturizer, and bathing regimen--washing only odor-bearing areas in lukewarm water with added bath oil--brought about marked improvement in the rash.

A contact dermatitis is not as well defined and tinea corporis usually is not as extensive as this rash. Viral exanthems do not last for several weeks. The distribution is slightly atypical for pityriasis rosea, but the disorder is included in the differential diagnosis.
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Case 2: D, Juvenile plantar dermatosis

Juvenile plantar dermatosis is seen in atopic patients with hyperhidrosis. It usually manifests as an erythematous rash on the distal third of the foot and spares the toe webs. Treatment includes keeping the foot dry (with foot powder and by frequently changing socks) and applying topical corticosteroid cream as needed. Patients outgrow this condition over a few years; it usually resolves by puberty.

Tinea pedis affects the toe webs but rarely involves the dorsum of the foot. This is an unlikely presentation for candidiasis, which generally affects immunocompromised persons--such as those with diabetes. Contact shoe dermatitis is common on the dorsum of the foot but rarely affects the toes. Hyperhidrosis does not cause a rash on the dorsum of the foot. *