Primary leiomyosarcoma of bone: a study of five cases.

Five cases of leiomyosarcoma of bone are described. The patients, 3 men and 2 women, ranged in age from 24 to 74 years. Four of the five tumors were located in the distal half of the femur. Radiographically, all tumors presented as purely osteolytic lesions. Angiography, performed in 3 cases, revealed hypervascularity and the presence of irregular, tortuous vessels at the site of the lesion in 1, but not in 2 others. Histologically, the five tumors showed features characteristic of leiomyosarcomas. The most prominent features were blunt-ended, cigar-like, chromatin-rich nuclei in elongated acidophilic cells arranged in bundles which intersected each other at wide angles. The importance of trichrome stains, such as van Gieson stain, for th recognition of leiomyosarcomas is emphasized. Electron microscopic examination, performed in 3 cases, showed as the most prominent features spindle-shaped cells in parallel arrangement containing abundant myofilaments which elongated densities, pinocytotic vesicles, and basal lamina structures.