osteodystrophia fibrosa

McCune-Albright syndrome

An autosomal dominant condition (OMIM:174800) due to altered regulation of cAMP, endocrinopathy (e.g., hyperthyroidism) and hypophosphatemia.

Clinical findings
Precocious puberty, polyostotic (cystic fibrous dysplasia) spontaneous fractures at young age, café-au-lait spots on skin, ovarian cysts.
 
Lab
Cyclical 4–6-week fluctuations of plasma oestrogen; afflicted young girls have decreased gonadotropins, decreased response to LH-RH; increased testosterone, increased alkaline phosphatase.
 
Molecular pathology
Defects in GNAS, which encodes a G protein that modulates various membrane signalling cascasdes, cause McCune-Albright syndrome.

Management
Aromatase inhibitor testolactone.

osteodystrophia fibrosa

a lesion of bone in which fibro-osseous tissue replaces resorbed bone. The resorption is caused by hyperparathyroidism which may be primary or, more commonly, secondary to nutritional error, or to renal insufficiency. Called also osteitis fibrosa, osteitis fibrosa cystica.

nutritional secondary osteodystrophia fibrosa
see nutritional secondary hyperparathyroidism.
renal secondary osteodystrophia fibrosa
see renal secondary hyperparathyroidism.