Paget’s Disease

Paget’s disease of the skull

This lateral skull xray demonstrates many of the changes of Paget’s disease, with areas of lysis, areas of sclerosis (‘cotton-wool spots’), and calvarial thickening.

The early phase of Paget disease is characterized by osteolysis on radiographs, an appearance that reflects the unopposed osteoclastic activity seen pathologically.

In the skull, osteolysis is frequently seen as well-defined, often large areas of radiolucency most commonly affecting the frontal and occipital bones; these areas are referred to as osteoporosis circumscripta or osteolysis circumscripta. Both inner and outer calvarial tables are involved, with the former usually more extensively affected. This pattern is in contradistinction to that of fibrous dysplasia, which usually affects the outer table more prominently. There is a notable absence of peripheral sclerosis surrounding the calvarial osteolysis secondary to the lack of significant osteoblastic activity. These areas of lysis are usually easily identified on radiographs, although it may be more difficult in patients with osteoporosis and correlative bone scans are helpful.

The vast majority of cases of Paget disease seen by radiologists are in the mixed phase. The characteristic manifestations seen radiographically are coarsening and thickening of the trabecular pattern and cortex as seen on this pelvic radiograph. These findings reflect the underlying pathologic changes of osteoblastic repair and are usually pathognomonic on radiographs. The trabecular thickening occurs primarily along the lines of stress. A lytic defect noted along the ileopectineal line is in keeping with mixed (lytic-sclerotic) phase of Paget disease.

REFERENCE – Stacy E. Smith, Mark D. Murphey, Kambiz Motamedi, Michael E. Mulligan, Charles S. Resnik, and Francis H. Gannon. From the Archives of the AFIP: Radiologic Spectrum of Paget Disease of Bone and Its Complications with Pathologic Correlation. RadioGraphics 2002; 22: 1191.

Credit: Dr Abhijit Datir