Mastocytosis and Hymenoptera venom allergy

Purpose of review Mastocytosis is a rare disease characterized by increased mast cells in skin and/or internal organs. We evaluate the impact of mastocytosis on diagnosis and treatment of Hymenoptera venom allergy. Recent findings Patients with Hymenoptera venom allergy who suffer from mastocytosis develop life-threatening sting reactions more often than those who do not. When patients with Hymenoptera venom allergy were systematically examined for mastocytosis, it was found to be represented to an abnormally high extent. Most patients with mastocytosis tolerate venom immunotherapy with no or only minor systemic symptoms. Venom immunotherapy was found to be marginally less effective in patients with mastocytosis than in those without evidence of mast cell disease (defined as absent cutaneous mastocytosis combined with a serum tryptase concentration of <11.4 mu g/l). Several deaths from sting reactions were reported in patients with mastocytosis after venom immunotherapy was stopped. These patients should have venom immunotherapy for the rest of their lives. Summary Patients suffering from mastocytosis and Hymenoptera venom allergy are at risk from a particularly severe sting anaphylaxis. They need optimal diagnosis and treatment. In patients presenting with Hymenoptera venom allergy, screening tests by measurement of serum tryptase concentration, and a careful skin examination are highly recommended.