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8-Year-Old Male with Red Patch on Shoulder

Can you diagnose this case?

David L. Kaplan, MD – 2015 Series Editor

Signs and Symptoms

The parents of an 8-year-old boy seek evaluation of a red patch on their son’s shoulder. The asymptomatic spot erupted 2 weeks earlier. The patient has seasonal allergies and frequently plays with his dog.

What does this look like to you?

Choose one to reveal diagnosis and discussion

Psoriasis
Tinea corporis
Impetigo
Contact dermatitis
Erythema migrans

Answer: Tinea corporis

See the full case at Consultant360

A potassium hydroxide evaluation, confirmed tinea corporis, which responded to a topical antifungal. The family was advised to have their dog examined by a veterinarian, since the pet was the suspected source of the dermatophyte.

Erythema migrans associated with Lyme disease was unlikely, since the patient had no prodromal symptoms and the lesion developed in winter, far beyond the tick bite transmission season. Because the single lesion was not pruritic and erupted on a site that was covered by clothing, patch tests for contact dermatitis were not warranted. The lesion demonstrated far less scale than is seen in psoriasis; the absence of tender, crusted vesicles ruled out impetigo.

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