Polyostotic Paget's disease. A search for lesions of different durations and for new lesions.

We conducted a medical record-based study of 169 patients with polyostotic involvement identified among 200 Paget's disease patients. Follow-up was 15 to 41 years in 31 cases. The pelvis was the only bone that was more likely than not to be involved bilaterally. All the other paired bones were more likely to be involved unilaterally and when both sides were involved the two lesions were very often frankly asymmetric. In a given patient, the duration of the various pagetic lesions, estimated from their size and from data provided by an earlier study on the rate of progression of pagetic lesions, was similar in some cases and showed marked differences in others. Aggregation of the lesions into two or three disease duration groups was seen in some patients, suggesting that Paget's disease may occur in two or three waves. When we reviewed the radiographs from 30 patients with a mean follow-up of 23 years, we found new lesions in ten patients. However, a review of bone scans from 18 patients with a mean follow-up of 11 years failed to uncover any firm evidence of new lesion development, perhaps because all these patients received bisphosphonate therapy (etidronate, tiludronate, pamidronate). We also found data suggesting that the disease process spread across a joint in some patients, even in the absence of degenerative joint disease. In particular, in several cases an extensive pagetic lesion was seen on one side of a joint and a considerably smaller lesion on the other side.