A 34-year-old man presented with a large cutaneous lesion on his left thigh that had started as a small papule when he was 13 years of age. The lesion had enlarged slowly over the last 21 years. The patient had received bacillus Calmette–Guérin (BCG) vaccination in childhood. The family history was significant for tuberculosis.
Clinical examination revealed a large, purplish-red, indurated plaque measuring 30 × 29 cm on the left thigh, extending to the buttock area. The edges of the lesion had a serpiginous contour with an involuted center (Fig. 1). A left inguinal lymph node was palpated.
Chest X-ray and blood cell count were normal. No other focus of disease was identified. Laboratory testing for human immunodeficiency virus (HIV) infection was negative. Purified protein derivative (PPD) intradermal injection disclosed a 19-mm skin induration.
Both the cutaneous lesion and the inguinal lymph node were biopsied. Histopathologic sections of the skin fragment showed epidermal hyperkeratosis, neovascular proliferation, and a dense dermal lymphocytic infiltrate. The histopathology of the lymph node demonstrated few granulomas with focal areas of central necrosis.
Staining for fungus was negative. Ziehl–Neelsen staining was negative on both the skin and lymph node specimens. Culture for fungus and Leishmania sp. was negative. Tissue culture on Lowenstein–Jensen medium from skin and lymph node was positive for Mycobacterium colonies after 5 and 7 weeks, respectively.
Multidrug therapy was instituted with rifampin 600 mg/day, isoniazid 400 mg/day, and pyrazinamide 2 g/day for 2 months, and then rifampin 600 mg/day and isoniazid 400 mg/day alone for the next 4 months. An excellent response was obtained at the end of treatment (Fig. 2).