Paget's Disease of Bone

= Osteitis Deformans

Definition: Disorganised bone metabolism.

Pathology: ?Slow virus infection of osteoclasts. EM: viral inclusion bodies in osteoclasts. PCR of reverse transcribed DNA suggests a paramyxovirus (?measles ?RSV ?canine distemper virus). 3–4% of Anglo-Saxons, but very rare outside of England. Incidence is higher in Lancashire towns.

Bone is large, deformed and vascular. Brittle. Histology: busy osteoclasts and osteoblasts. Defective mineralisation (matrix changes too quickly). Cement lines, mosaic appearance.

Clinical features

  1. asmptomatic
  2. bone pain
  3. pathological fractures
  4. deformed bones ("tam-o'-shanter" vault, sabre tibia, kyphosis)
  5. nerve compression (multiple crainial nerve palsies, paraplegia, corda equina lesions)
  6. high output heart failure
  7. osteogenic sarcoma

Investigations

  1. ↑ alk phos
  2. Ca, PO4 not elevated
  3. radiology: thickened, sclerotic, deformed bone.

Treatment

  1. analgesia
  2. bisphosphonates
  3. calcitonin (ineffective after 3/12)
  4. surgery (to correct deformity)

Differential Diagnosis

  1. Osteomalacia
  2. Malignancy
  3. Fibrous dysplasia
  4. Fibrogenesis imperfecta ossium