Would You Biopsy This Persistent Red Patch?

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 a few months, a 47-year-old man has noted a persistent, asymptomatic patch on his upper arm. The patient has no significant medical problems, takes no medications, and has no history of seasonal allergies. He keeps a pet cat and enjoys gardening.

Do you recognize this lesion?

A. Nummular eczema.
B. Basal cell carcinoma.
C. Actinic keratosis.
D. Pityriasis rosea.
E. Tinea corporis.

What do you do now?

F. Prescribe an antifungal antibiotic.
G. Perform a potassium hydroxide evaluation.
H. Perform a complete laboratory workup.
I. Perform a skin biopsy.
J. Observe and follow up in 3 months.

Answer: Basal cell carcinoma

A skin biopsy, I, confirmed the clinical suspicion of basal cell carcinoma, B. Because the patient worked shirtless every summer in his garden, actinic keratosis was a diagnostic consideration. The basal cell carcinoma was excised completely, and the patient was instructed to use sunscreen when exposure to the sun could not be avoided.

This asymptomatic lesion was neither pruritic nor scaly, thus ruling out nummular eczema and pityriasis rosea, respectively. Fungal infections generally are scaly and often pruritic; although they expand slowly, they do so more quickly than basal cell carcinoma.