Derm Dx: Trunk dermatitis that does not fluoresce under Wood's light

An African American man, aged 38 years, presents for evaluation of an extensive rash involving his chest and back. The dermatitis began as a small patch several months ago and spread rapidly despite treatment with topical ketoconazole shampoo and triamcinolone cream. He denies significant pruritus. Examination reveals hyperpigmented patches with scale on the affected areas. Fluorescence was not observed under ...