Multiple diffuse fibrosarcoma of bone.

Light and electron microscopic observations of a case of multiple diffuse fibrosarcoma of bone are presented. Two cases of diffuse fibrosarcoma of bone have been previously reported. Clinically the tumor presented as multiple osteolytic lesions involving the pelvis bone, vertebral bodies and skull with the radiologic appearance of a multiple plasma cell myeloma. Histologically the tumor was a spindle-cell fibrosarcoma. At the ultrastructural level the tumor cells represent fibroblasts separated by a scanty amount of collagen fibers. Electron microscopic findings substantiate the fibroblastic origin of multiple diffuse fibrosarcoma of bone.