[Giant cell tumors developing in Paget's disease. Presentation of 2 cases with an ultrastructural study].

We report two cases of giant cell tumor of bone (osteoclastoma) associated with Paget's disease. One appeared on the left cubitus in a 68-year-old male patient while the second involved the right maxillary sinus in a 79-year-old woman. Histopathological study was completed by ultrastructural and immunocytological studies. They were demonstrated to contain intranuclear virus-like filamentous inclusions in the osteoclasts. However, we cannot obtain positive response with antisera against measles virus and respiratory syncitial virus. These data are confronted to the hypothesis for a viral aetiology of Paget's disease and giant cell tumor of bone, associated or not to Paget's disease.