Why has this annular rash resisted antifungals?

Case:

A 45-year-old man presents with a 4- to 5-year history of an intermittent, asymptomatic, red, circular rash on his trunk. Trials of antifungal creams have not been successful. The patient is otherwise healthy and takes no medications.

A skin biopsy, I, confirmed the suspected diagnosis of erythema annulare centrifugum, E. This annular eruption is a reaction to a variety of antigenic stimuli, including infectious, inflammatory, and neoplastic processes. The cause of this patient's disease remains unknown. The lesions usually respond to topical corticosteroids.

Subacute cutaneous lupus is also a gyrate eruption, but it usually is found on sun-exposed surfaces. Pityriasis rosea typically is itchy and self-limited, lasting weeks to months. Erythema chronicum migrans often is associated with Lyme disease, is self-limited, and presents with slowly enlarging singular or multiple annular lesions. Tinea corporis does not disappear and reappear.