Osteitis fibrosa cystica

Osteitis fibrosa cystica describes the advanced bony changes seen in patients with primary or secondary hyperparathyroidism. It is now rare as hyperparathyroidism is usually discovered and treated at an earlier stage than before.

Advancing hyperparathyroidism produces a sequence of bony changes:

• demineralisation
• osteitis fibrosa - increased osteoclastic activity with bone resorption and peritrabecular fibrosis
• osteitis fibrosa cystica is characterised by:
  • extensive bone resorption accompanies marrow fibrosis with the development of cysts within the enlarged fibrotic marrow spaces
  • brown tumours

Skeletal changes are most prominent at the sites of highest bone activity - trabecular bones of vertebrae, phalanges, the ends of long bones, and parts of the skull.

Osteitis fibrosa cystica is most common in severe primary hyperparathyroidism. Secondary hyperparathyroidism due to chronic renal failure usually produces renal osteodystrophy.