Comparison of the ultrastructure of a malignant tumor of the mandible containing giant cells with Paget's disease of bone.

Distinction between lesions of the jaws containing giant cells can be difficult. This study reports the results of the study of the ultrastructure of 30 patients with Paget's disease in comparison with a patient diagnosed as having malignant giant cell tumor of the mandible. The ultrastructure of the malignant giant cell tumor of the mandible was found to contain nuclear inclusions morphologically identical with the 12-15 nm tubules characteristic of the nuclei of osteoclasts in Paget's disease of bone. No clinical or laboratory signs of Paget's disease was found in this patient. A search of the literature failed to produce reports of identical nuclear inclusions in soft tissue giant cell tumors, osteosarcomas, reparative granulomas containing giant cells or in osteitis fibrosa cystica. Such nuclear inclusions have been reported in benign giant cell tumors of bone, one another in malignant giant cell tumor and cases of polymyositis. These observations raise the question of a possible virus associated with the tumor since there are recent reports of immunological evidence for the presence of a virus in Paget's disease, and viruses have been suspected in polymyositis.