Systemic mastocytosis presenting as osteoporosis--a case report.

Mastocytosis is a clonal disorder of the mast cell and its precursor cells, and is characterised by proliferation and accumulation of mast cells within various organs, most commonly the skin. Systemic mastocytosis is a rare but well-recognised cause of secondary osteoporosis, accounting for about 1.25% of cases. The pathophysiological mechanism is probably multifactorial, including increased osteoclastic activity, and a direct effect of mast cell mediators like histamine, heparin, tryptase and cytokines. Here, we report the case of a middle-aged male patient with osteoporotic vertebral fractures as a rare presenting manifestation of systemic mastocytosis. In summary, systemic mastocytosis, although rare, should be considered as a cause in patients with idiopathic osteoporosis.