Osteosarcoma in Paget Disease of Bone

Comments:
Introduction: Paget sarcoma is a rare complication that is mainly seen in elderly patients with extensive Paget disease of bone (PDB). The reported incidence ranges from 0.7-6.3% of cases; however, since most cases of PDB remain undiagnosed, the true incidence of sarcoma is quite low. It is believed to be 0.3-0.5% for all cases of PDB and <10% for those with most severe involvement.

Clinical Features: Most patients are in their 6th or 7th decade. In areas where PDB is endemic, nearly 50% of bone sarcomas in patients older than 50 years occur in the setting of PDB. Two-thirds of Paget sarcomas involve long bones and remaining one-third occur in flat bones. The most common sites are proximal femur (34%), pelvis (24%), proximal humerus (24%), and skull (15%). It is rare in spine (2%). The tumor may be multifocal in up to 15% of cases. Malignant transformation is often heralded by onset of new pain and swelling or pathologic fracture in a patient with severe polyostotic PDB.

Slide courtesy of Piero Picci, M.D., Director, Laboratory of Experimental Oncology, Instituto Ortopedico Rizzoli, Bologna, Italy. Used with permission.