Annular scaly erythematous plaque on the right chest

A woman in her 80s presented to dermatology with a three year history of a persisting, mildly pruritic, annular, infiltrated, erythematous plaquewith crusts and scales on the right side of her chest (fig 1). She said this area was frequently exposed to the sun in the summer, when she would usually wear vests. Despite treatment with topical corticosteroids and antifungal ointment for variousperiods over the three years, the lesion persisted with only slight improvement. Microscopic examination of scales for fungi (potassium hydroxide test) was negative.