Paget’s Disease of Bone, and Sarcoma Complicating Paget’s Disease

Abstract

Paget’s disease is a chronic disease of bone due to hyperactivity of osteoclasts and osteoblasts that results in abnormal bone remodeling. Lesions may be monostotic or polyostotic. It is most common in Northern European people and is twice as common in males than in females. It is more frequent after the fourth decade. The innominate bone and femur are the most common locations, followed by the lumbar spine, skull, and tibia. Radiologically, in the early stage, the lesion is sharply marginated, lytic, and radiolucent. In the skull it is called osteoporosis circumscripta. The transition between the lesion and the normal cortex is sharp and wedge-shaped. In an intermediate stage, radiolucency and radiodensity alternate, reflecting the histopathological picture. The cancellous bone presents thicker, irregular, and coarser trabeculae; thickening of the cortex; and increased bone diameter. The late stage shows increased density, with bone thickening. Bowing bone deformity (more common in the femur and tibia) is due to the altered mechanical properties of pagetic bones. Fractures are also seen in pagetic bones. In the spine, the diameter of affected vertebral bodies increases, as seen in anteroposterior and lateral X-rays.

Histologically, the osteolytic stage shows very active osteoclastic resorption removing normal lamellar bone as well as some immature woven bone formation by active osteoblasts. The osteoblastic stage is characterized by wide bone trabeculae with the characteristic “mosaic pattern” due to numerous reversal-type cement lines.

Sarcoma complicates Paget’s disease in about 1% of patients with Paget’s. There is a slight predominance of men, most often between 50 and 70 years of age. The most frequent sites are the femur, humerus, pelvis, and tibia. The most common tumor type is osteosarcoma, followed by fibrosarcoma. Less frequent are chondrosarcoma, undifferentiated high grade sarcoma and lymphoma.

Treatment of Paget’s disease includes the use of calcitonin and bisphosphonates to reduce symptoms by reducing bone turnover, with surgery for pathologic fractures. Sarcomas associated with Paget’s disease are treated with surgical resection, amputation, or disarticulation. Radiotherapy and chemotherapy are indicated.

Eduardo Santini-Araujo was deceased at the time of publication.