ABSTRACT
Purpose To explore the clinicopathological features, diagnosis and differential diagnosis of primary leiomyosarcoma of bone and to study its therapy and prognosis. Methods Histopathologic features, immunohistochemical stains and iconography of five cases were analyzed and the related literatures were reviewed. Results The patients consisted of two males and three females with ages ran-ging from 46 to 72 years, who average 58 years. Clinically, most cases presented as pain reaction, of which two cases were located a-round the knee joint, one case was in the upper femur, one case was in the sacrum and another was in the upper jaw. Microscopically, tumor cells were composed of spindle shaped cells, with some epitheloid variants. Immunohistochemically, all the tumor cells were pos-itive for smooth muscle actin and vimentin, and the expression of desmin was found in two cases. But S-100 protein, MyoD1 and CD68 were negative. Conclusions Primary leiomyosarcoma of bone is relatively rare, and clinical symptoms and imaging findings are not specific. The diagnosis depends on immunohistochemistry and electron microscopy.