Clinical Challenge: Dermatitis Over the Torso That Looks Like an Allergic Rash

A 28-year-old Hispanic woman presents for evaluation of a minimally pruritic dermatitis involving her chest, back, and abdomen. The rash began three weeks ago at which time she was diagnosed elsewhere with an "allergic reaction" and placed on cetirizine. Examination reveals multiple erythematous to hyperpigmented papulosquamoid patches. Her palms, soles, and oral mucosa are unaffected. She insists on a biopsy ...