Complementary Scintigraphy in Tuberculous Osteomyelitis

A 26-year-old man had persistent pain and increased swelling in the anterior aspect of the upper left leg, 2 months after an episode of trauma to his left leg. He was afebrile and had no systemic symptoms. Plain radiographs revealed an ill-defined irregular lytic lesion in the anterior aspect of the proximal tibia. Scintigraphy with Tc-99m MDP showed marked localized hyperemia and intense focal osteoblastic activity in the left proximal tibia, anteriorly. Marked preferential accumulation of Tl-201 was apparent in the same site. However, only a moderate degree of Ga-67 uptake was present in this lesion in 24-hour imaging. No abnormal sites of accumulation of any of the three agents were demonstrated elsewhere. The combined scan appearances favored a primary bone neoplasm, chronic osteomyelitis being less likely in view of the observation that the Tl-201 avidity in the lesion was so much greater than that of Ga-67. A CT scan revealed a lytic area, 15 mm in diameter with a slightly sclerotic rim, that contained a sequestrum of bone. A thin track through the anteromedial cortex to the overlying soft tissues with subcutaneous soft tissue swelling was also demonstrated, consistent with a cloaca. A biopsy specimen revealed pus and microscopy confirmed tuberculous osteomyelitis, with no evidence of malignancy. Chest radiography prior to commencing antituberculous chemotherapy yielded normal findings.