A 63-year-old female patient had an indurated, infiltrated erythematous-ferruginous plaque with central atrophic scars (from previous biopsies) on her right leg (Figure 1). She had been treated with antibiotics, antifungal and corticosteroid therapy with no improvement. We repeated the biopsy and the lesion progressed to a 6-cm ulcer with irregular borders and fibrino-necrotic areas (Figure 2). The following tests were normal: blood cell count, VDRL, ANA, AFB in the lymph nodes, HIV, culture for bacteria and fungi (in biopsy material), serology for leishmaniasis, and radiography of the chest and legs. ESR was 48 mm/hour and PPD was nonreactive. The anatomicopathological study showed histiocytes and multinucleated giant cells (Figure 3). Culture was positive for AFB. PCR (polymerase chain reaction) revealed genotypic characters of Mycobacterium tuberculosis (primers TB1 (primers: TB1 (5'-CCTGCGAGCGTAGGCGTCGG-3') and TB2 (5'-CTCGTCCAGCGCCGCTTCGG-3')), which amplify a fragment of 123 base-pairs (bp) of the IS6110 sequence (Figure 4). The treatment was performed with pyrazinamide, rifampicin, isoniazid and ethambutol.