Breaking point: Systemic mastocytosis manifesting as severe osteoporosis.

Systemic mastocytosis (SM) encompasses a wide spectrum of myeloproliferative disorders defined by the aggregation of abnormal mast cells in various tissues, including the bone marrow, gastrointestinal tract, liver and lymph nodes. The release of tryptase, interleukins and cytokines by the accumulated mast cells causes a multi-system response that can range from mild flushing and pruritus to severe anaphylactic reactions, gastrointestinal disturbances, and cardiovascular symptoms, including hypotension and syncope. Furthermore, severe osteoporosis manifesting as bone-lytic lesions or pathologic fractures due to mast cell mediator-triggered bone resorption, is a rather common manifestation of SM, occurring in more than two-thirds of patients.