Drug-induced anaphylaxis uncommon in mastocytosis: findings from two large cohorts

Background Anaphylaxis is a common feature of mastocytosis patients, particularly with Hymenoptera venoms. Hence, it is hypothesized that mastocytosis patients may have an increased susceptibility to developing drug-induced anaphylaxis (DIA). Patients and medical practitioners are therefore concerned when there is a need to use various drugs. However, this issue has not been systematically investigated. Objective Our study aimed to investigate the prevalence and clinical characteristics of anaphylaxis to various types of drugs among mastocytosis patients. Methods A retrospective study was conducted among 470 consecutive patients (≥ 18 years) with confirmed clonal mast cell diseases recruited from two independent mastocytosis reference centers. All patients underwent a comprehensive, individualized allergy workup with evaluation of the (self)reported drug hypersensitivity. Results Overall prevalence of DIA was 6.3% accounting for 1/3 of the confirmed drug hypersensitivity reactions. Non-steroidal anti-inflammatory drugs (NSAIDs) were the most common elicitors of DIA (56%), followed by perioperative agents (23%) and antibiotics (13%). Anaphylactic reactions were severe in most cases with 43% of patients experiencing hypotensive syncope. All drug-related hypersensitivity reactions occurred before mastocytosis was diagnosed. Conclusions The prevalence of DIA in mastocytosis tends to be higher than in general population, but is overall low. However, its severity is more pronounced. Our results suggest that mastocytosis patients with a prior reaction to drugs should undergo a thorough allergy workup. Well-tolerated drugs can be further used without specific precautions.