Giant cell reparative granuloma of Paget's disease of bone: a unique clinical entity.

Giant cell tumor of bone is a rare, but well-recognized complication of Paget's disease of bone. In contrast, giant cell reparative granuloma (a benign tumor of the jaws occurring primarily in young adults) has never been described in association with Paget's disease. Five patients had giant cell lesions complicating Paget's disease. In each instance, the lesion histologically more closely resembled reparative granuloma than true giant cell tumor. The location of these lesions and their sensitivity to irradiation were consistent with reparative granuloma. Unique features included the frequency of polyostotic distribution, the occurrence only in bones affected by Paget's disease, and an apparent familial or geographic clustering of the patients. We also reviewed the histologic findings of three patients from another institution and compared the cases of all eight patients with others we believe were incorrectly diagnosed as having benign giant cell tumors in Paget's disease. We suggest that giant cell reparative granuloma of Paget's disease is a unique clinical entity with specific prognostic and therapeutic implications.