Bone tissue in Paget's disease treated by ethane-1, hydroxy-1, 1 diphosphonate (EHDP). Structure, ultrastructure, and immunocytology.

Diphosphonates have been used in the management of Paget's disease of bone because of their experimentally demonstrated antiosteoclastic activity. Light microscopic examination of bone tissue from 13 patients with Paget's bone disease who were receiving (EHDP) treatment showed considerably reduced osteoclastic resorption accompanied by gradual replacement of irregular woven bone by lamellar tissue. Electron microscopic examination confirmed that pagetoid osteoclasts are morphologically abnormal cells and degenerate after EHDP treatment. EHDP does not affect the measles nucleocapsid-like inclusions in the osteoclast nuclei. Immunocytologic analysis showed that during EHDP treatment viral antigens of the measles type persist in the cytoplasm and nuclei of osteoclasts even when these cells are greatly altered. These findings support the hypothesis of a viral etiology in Paget's disease of bone.