Mastocytosis and insect venom allergy: a special relationship

Abstract Mastocytosis, a clonal mast cell disorder, is strongly associated with severe insect venom allergy. This review summarizes the pathophysiologic mechanisms linking mastocytosis and Hymenoptera venom anaphylaxis and discusses diagnostic and therapeutic strategies. Patients with mastocytosis are at markedly increased risk for sting-induced anaphylaxis, often presenting with cardiovascular collapse and minimal cutaneous signs. Clonal mast cell expansion, usually driven by KIT D816V, lowers the threshold for mediator release. Baseline tryptase is typically elevated, but normal levels do not exclude disease, as occult mastocytosis may still be present. Hereditary alpha-tryptasemia (HαT), a genetic trait causing elevated tryptase, further increases risk and may coexist with mastocytosis. The diagnostic work-up in patients with venom allergy should include serum tryptase, venom-specific IgE (with component-resolved diagnostics), and KIT mutation analysis in patients with severe reactions. Bone marrow biopsy is indicated if suspicion remains high. Detection of KIT D816V is an independent predictor of severe sting reactions. Venom immunotherapy (VIT) is highly effective and lifesaving but associated with more frequent systemic reactions in mastocytosis (> 20%). Omalizumab may improve VIT safety in high-risk cases. Given the high relapse risk, lifelong VIT is recommended, along with epinephrine autoinjectors and rigorous emergency preparedness. Personalized management including risk stratification by KIT and HαT status, optimized VIT protocols, adjunctive therapy, and patient education is essential. Mastocytosis and venom allergy form a unique clinical constellation requiring proactive diagnosis and individualized long-term management to prevent fatal reactions.