Primary leiomyosarcoma of bone

We report a case of primary leiomyosarcoma in the right femoral diaphysis. Conventional radiographs revealed an indistinct osteolytic lesion with a ve ry subtle periosteal reaction. MR imaging revealed an intramedullary lesion with a well-defined margin, cortical breakthrough and soft tissue extensio n. The lesion was isointense relative to muscle on T1-weighted imaging, iso -hypointense relative to fat on fast spin echo T2-weighted imaging, and hyp erintense to muscle on fast spin echo T2-weighted imaging with fat saturati on. A peripheral rim and intratumoral spoke-wheel-like enhancement in the s oft tissue component of the tumor was noted on gadolinium-enhanced T1-weigh ted imaging with fat saturation. Such an enhancing pattern, which has not b een described in the literature previously but has been seen in leiomyosarc omas elsewhere by both MR imaging and computed tomography, deserves further pathological correlation.