- Etiology: disease may be caused by a virus;
- paramyxovirus infection of osteoblasts may activate of the c-fos proto-oncogene, resulting in
localized abnormal osteoclastic activity typical of Paget's disease;
- Pathophysiology:
- in Paget's disease, primary defect is in the remodeling system of isolated areas of skeleton;
- it is characterized by massive turnover of bone in the affected areas w/ marked increase in both
bone resorption & bone formation;
- owing to rapid turnover, the bone formed is immature bone;
- in the bones affected, there may be either little change in the shape of the bone or very marked change in the bone
contour resulting from both lack of appropriate remodeling & change in quality of bone;
- small increased risk of osteosarcoma;
- Hypervascular / Osteolytic Phase:
- initial phase of disorder involves bone resorption by
osteoclasts;
- subsequently there is vigorous osteoblastic response, producing excessive, poorly organized, structurally weak,
highly vascular woven bone;
- disease causes significant increase in blood flow of involved bones;
- this increase may be so extensive, due to small arteriovenous shunts, that cardiac output is significantly increased;
- degenerative arthritis is assoc w/ hypervascularity of ends of bones;
- after some time osteoclastic activity subsides & woven bone is replaced by lamellar bone as the osteoblastic action persists;
- Intermediate Phase:
- in this phase osteoblastic activity predominates, but osteolytic activity is also present and therefore,
and bone structural changes and bone deformity are manifest;
- Quiescent stage:
- finally, osteoblastic activity diminishes & bone becomes quiescent, w/ bony sclerosis and no
evidence of increased turnover of bone, and bone enlargment and widening;
- vascular fibrous tissue replaces the marrow;
- Haversian systems are absent;
On the trail of paramyxoviruses in Paget's disease of bone.
Pathogenesis of Paget's disease based on viral etiology.
Critical evaluation of viral antigen data in Paget's disease of bone.
