Derm Dx: Erythematous patches on the member

A patient, aged 65 years, presented with an asymptomatic eruption of his penis. He denied prior episode of a similar rash, recent sexual contact, commencement of any new medications, and history of skin disease.

Examination revealed shiny, well-demarcated erythematous patches of the corona and prepuce. No exudates or vesicles were apparent, and inguinal nodes were nonpapable.

The patient was treated with ...