Ruling Out the Diagnosis

Abstract

I SAW A PATIENT along with a dermatology resident. The patient was a black woman with several papules and a plaque on her thigh. The plaque was slightly larger than 1 cm in diameter, hyperpigmented, and had a thin raised border. The papules were 3 to 5 mm, flat topped, and similarly hyperpigmented. None of the lesions was erythematous. The patient had no oral lesions and had normal nails. Despite the lack of Wickham's striae and an atypical location and appearance, we agreed that lichen planus was the most likely diagnosis. The papules had the characteristic flat-topped morphology. Pigment incontinence is a prominent feature of lichen planus. 1,2 Erythema is often difficult to discern in dark skin. 3 Sarcoidosis and granuloma annulare were considered in the differential diagnosis but were considered much less likely. A 4-mm punch biopsy specimen was obtained to confirm the diagnosis. Several days later I received