A female patient, aged 24...

A female patient, aged 24, presented with a painful lesion on her right buttock that had steadily increased over four years. The lesion was a large, reddish-brown, scaly plaque with well-defined edges and central atrophic alterations covering the entire right buttock area (Fig 1). The lesion was painful and warm, with a sensitivity to a mild touch of purulent material through several fissures along the perimeter. On physical examination, the patient's vital signs were normal, the skin showed no other significant abnormalities, and lymphadenopathy was absent. Medical history included psoriasis and the presence of a comparable lesion (on her neck) as a child which was medically excised. The patient had received Bacille Calmette-Guérin (BCG) vaccine in the past. Skin biopsy and serum QuantiFERON®-TB Gold tests were done, and histology of the plaque revealed pseudoepitheliomatous hyperplasia and neutrophilic microabscesses in the epidermis. A neutrophilic and granulomatous infiltration was observed in the dermis (Fig 2 and 3). AFB staining displayed untypical elongated acid-fast structures indicative of tuberculosis infection (Fig 4) Mycobacterium tuberculosis was cultured from lesional tissue, and serum QFT-G tests were positive. Sputum cultures were negative, and a chest x-ray revealed no signs of active pulmonary infection.