Tinea Corporis

Why Do These Patches Recur Each Winter?

DAVID L. KAPLAN, MD—Series Editor
Dr Kaplan is clinical assistant professor of dermatology at the University of Missouri Kansas City School of Medicine and at the University of Kansas School of Medicine. He practices adult and pediatric dermatology in Overland Park, Kan.

For the past few weeks, pruritic patches have been erupting on a 38-year-old man’s extremities. He recalls that similar lesions occurred during the past 2 winters. The patient has a history of seasonal allergies; he owns a cat and 2 dogs.

Your clinical impression is...

A. Nummular eczema.
B. Ringworm.
C. Psoriasis.
D. Contact dermatitis.
E. Pityriasis rosea.

What action do you take?

F. Perform a skin biopsy.
G. Perform a potassium hydroxide evaluation.
H. Recommend the use of mild soaps and moisturizers.
I. Recommend that a veterinarian examine the pets.
J. Prescribe a corticosteroid cream.

Answer: Nummular eczema

Multiple, pruritic, coin-shaped lesions that erupt during cold weather—particularly in persons with atopy—strongly suggest nummular eczema, A. Typically, only 1 or 2 inflamed lesions occur when a pet is the source of ringworm, which can be ruled out by a potassium hydroxide evaluation, G.

The lesions of contact dermatitis usually are less well-defined and generally occur on exposed areas; because it was winter, this patient’s arms and legs had been covered. Pityriasis rosea arises on the trunk, and psoriasis affects the knees and elbows, which were clear in this patient.

The seasonal recurrence of multiple lesions is not a feature of skin cancer; thus, a biopsy was not warranted. The patient was advised to use a mild soap and to apply moisturizer assiduously, H, to his sensitive skin. The eczema responded quickly to a topical corticosteroid, J.