Osteoclast ultrastructure in Paget's disease.

The ultrastructural study of osteoclasts in biopsies from 12 patients with Paget's disease reveals several cytological anomalies. In Particular, nuclear inclusions, consisting essentially of striated filaments about 150 A in diameter, often organized in bundles and sometimes in paracrystalline arrays, appear to be specific to the disease. Morphologically, the inclusions are remarkably similar to those observed in various cases of viral attack, and the hypothesis of the action of a possible external agent in Paget's disease cannot be ruled out.