A 23-year-old black man complained of a nonpruritic, peripherally growing, annular erythematous eruption that had first appeared on his cheek four weeks ago. The lesion had a slightly raised bright red border with fine trailing scales inside the advancing edge. Tests for fungus were negative. Biopsy of the active border showed discrete parakeratosis, spongiosis, and a superficial lymphohistiocytic infiltrate. Three months earlier, the patient had begun divalproex sodium (Depakote) for treatment of migraine headaches.