Paget Disease of Bone : Introduction

Comments:
Introduction: Paget disease of bone (PDB) is a chronic, non-neoplastic, metabolic disorder in which there is abnormal bone remodeling in localized areas of skeleton. There is excessive bone resorption by abnormal multinucleated osteoclasts that is followed by disorganized bone formation by osteoblasts. The newly formed woven bone is mechanically weak and subject to deformity and fractures. This disorder was first described in 1877 by English pathologist and surgeon Sir James Paget, who referred to it as osteitis deformans.

PDB is the 2nd most common metabolic bone disorder after osteoporosis. It is common in the populations of northern Europe and quite rare in Asians and Blacks. The disruption of normal cycle of bone remodeling and renewal can involve a single site (monostotic) or multiple skeletal sites (polyostotic).

Most patients are asymptomatic and the disease is discovered incidentally on imaging studies or elevated serum alkaline phosphatase level. Genetics (mutations in sequestosome 1 (SQSTM1) gene coding p62 protein) and virus infection (possibly paramyxoviruses) are thought to play a role in its pathogenesis.

About this image: Mixed lytic and blastic phase of PDB showing osteoclastic resorption, marrow fibrosis, and new bone formation. Note the numerous osteoclasts engaged in chewing away bone and creating scalloped edges along bony trabeculae, while simultaneously there is new bone formation by osteoblasts, often within the same trabeculae.