No abstract

Clonal mast cell disorders (cMCD) comprise systemic mastocytosis (SM) and monoclonal mast cell activation syndrome (MMAS). 1,2 Common to these two conditions is the presence of mast cell (MC) clonality, as reflected in a mutation in codon 816 of KIT and/or occurrence of immunophenotypically aberrant MCs expressing CD25. 3 In patients with MMAS, the WHO criteria for SM are not fully met. 3 Anaphylaxis is a well-known feature of cMCD; particularly, venom allergy represents an increased risk of severe, even fatal, sting anaphylaxis in these patients. 4,5 Although the overall prevalence of Hymenoptera venom-induced anaphylaxis (HVA) is approximately 25% in patients with SM, 6 the underlying reason(s) for this association remains elusive. The aggravated risk of severe HVA might be due to increased MC burden, perivascular aggregation of MCs and an amplified IgE reaction due to the presence of D816V KIT mutation. 7 These findings stress the importance of

BackgroundAnaphylaxis is a well-known feature of mastocytosis, particularly in relation to hymenoptera venom stings. It is therefore hypothesized that mastocytosis patients may also be predisposed to severe hypersensitivity reactions to certain medications including non-steroidal anti-inflammatory drugs (NSAIDs). For this reason, these patients are usually discouraged from using these drugs. The current study aimed to determine the prevalence and evaluate the severity of NSAID-related hypersensitivity reactions among patients with mastocytosis.MethodsA retrospective study was conducted among a total of 388 (≥18 years old) consecutive patients from two independent European mastocytosis centers, in Sweden and Italy. Patients underwent a thorough allergy work-up where self-reported NSAID-hypersensitivity reactions were re-evaluated by an allergist in the first cohort (202 patients) and results were validated in the second cohort (186 patients).ResultsOverall frequency of NSAID-hypersensitivity was 11.3% in the total study cohort. Most patients reacted with cutaneous symptoms (89%), whereas severe hypersensitivity reactions were infrequent with only 11 patients (2.8%) experiencing anaphylaxis. All NSAID-related hypersensitivity reactions had occurred before mastocytosis was diagnosed. There was no difference between the groups regarding gender, baseline tryptase levels or presence of atopy, asthma/rhinitis.ConclusionOur study indicates an approximate 4-fold increased prevalence of NSAID hypersensitivity among mastocytosis patients compared to the general population. However, most NSAID reactions were limited to the skin as the prevalence of overall anaphylaxis was infrequent. Our results support that mastocytosis patients with a known tolerance to NSAIDs can continue using these medications without special precautions, whereas those with a prior reaction to NSAIDs should undergo thorough allergy work-up, including drug challenges.