Clinical usefulness of thallium-201 scintigraphy and magnetic resonance imaging in the diagnosis of chondromyxoid fibroma.

Chondromyxoid fibroma (CMF) is a benign bone tumor. However, it is sometimes difficult to distinguish this tumor from chondrosarcoma. We report a rare case arising from the proximal fibula, presenting multimodality imaging features. An 18-year-old man presented with a 2-year history of gradually increasing pain and swelling in his left knee. Radiograph showed an area of osteolysis with lobulation. Magnetic resonance (MR) imaging demonstrated that almost the whole lesion was enhanced with Gd-DTPA. Scintigraphy examination with (99m)Tc-biphosphonate showed strong accumulation in the periphery. On Ga-67-citrate scintigraphy, there was a little uptake. Thallium-201 scintigraphy showed strong accumulation of the whole lesion in early and late scans. The tumor was diagnosed as CMF by open biopsy. It is important that CMF is correctly distinguished from other tumors because this may be histologically overdiagnosed as chondrosarcoma. Contrast-enhanced MR imaging and thallium-201 scintigraphy may be useful to distinguish CMF from benign bone tumors or chondrosarcoma.