Does this scaling rash signal an underlying disorder?

March 3, 2010

A 35-year-old man presents with a scaling rash on the penis of several weeks’ duration. Which of the following would you include in the differential?

Case 3:

A 35-year-old man presents with a scaling rash on the penis of several weeks' duration. Which of the following would you include in the differential?

A. Candidiasis.
B. Dermatophyte infection.
C. Lichen planus.
D. Seborrhea.
E. Psoriasis.

Answers on next page

In this patient, a positive potassium hydroxide (KOH) examination confirmed dermatophyte infection, B. Dermatophyte infections of the penis and scrotum are relatively rare compared with those that involve the groin. Underlying conditions that can produce an immunocompromised state should be investigated, including diabetes mellitus.

This dermatophyte infection should respond to topical antifungal therapy.

The purple polygonal lesions of lichen planus are unlike the rash seen here. However, the other conditions are reasonable to consider in the differential, and a KOH examination is needed to rule them out.