[Mastocytosis: an important differential diagnosis in anaphylactoid reaction to Hymenoptera sting. A case report and overview of clinical aspects, diagnosis and current therapy of mastocytosis].

A 77-year old farmer presented with a history of three severe anaphylactoid reactions after hymenoptera stings for the last three years. No sensitisation to hymenoptera venoms could be shown on allergological work-up. The serum level of tryptase however was clearly elevated (37.1 micrograms/l; normal value: < 13.5 micrograms/l). The diagnosis of systemic mastocytosis could be confirmed by bone marrow biopsy. Patients with mastocytosis are at increased risk of anaphylactic/anaphylactoid reactions. They should be educated how to avoid trigger factors and they should always carry an emergency kit (H1 blocker, corticosteroid, adrenalin) and a "mastocytosis pass" with them. Venom immunotherapy is indicated in patients with proven hymenoptera allergy. Selected patients at very high risk of anaphylactic reactions may need a continuous prophylactic medication with H1 and H2 blocker and eventually a cyclooxygenase inhibitor.