Intraosseous leiomyoma: a report of two cases

Intraosseous leiomyoma is an exceedingly rare tumor, with about 15 cases in the literature. Gradually worsening nonspecific pain is the main manifestation. A unilocular or multilocular radiolucency with a rim of sclerosis is seen on standard radiographs. The findings may simulate nonossifying fibroma of a metaphysis or histiocytofibroma of the pelvis. Neither computed tomography nor magnetic resonance imaging can establish the definitive diagnosis, which requires histological examination with immunohistochemistry stains. Intraosseous leiomyosarcoma is the main differential diagnosis. The best discriminating criterion is the mitotic index, which is less than 1 to 4 mitoses per 50 high-power fields in leiomyomas. En bloc excision with wide margins is the treatment of choice for avoiding local recurrences, which are extremely rare.