[Intranuclear inclusions in giant cell bone tumor. Demonstration by electron microscopy].

In a case of giant cell tumour of bone, electron microscopy revealed filamentous inclusions within the nuclei of all the giant cells. Although not invariably present in such tumours, their similarity with the nucleocytoplasmic inclusions seen in osteoclasts in Paget's disease is underlined. This raises interesting questions as to their nature and the histogenesis of these disorders.