Objective

We aimed to determine the clinical and laboratory features of ISMs^{鈭?/sup> associated with insect-induced anaphylaxis (insectISMs鈭?/sup>) versus other patients with ISM.}

Methods

A total of 335 patients presenting with MC activation syndrome, including 143 insectISMs^{鈭?/sup>, 72 ISMs鈭?/sup> triggered by other factors (otherISMs鈭?/sup>), 56 ISMs+, and 64 nonclonal MC activation syndrome, were studied.}

Results

Compared with otherISMs^{鈭?/sup> and ISMs+ patients, insectISMs鈭?/sup> cases showed marked male predominance (78% vs聽53% and 46%; P聽< .001), a distinct pattern of MC-related symptoms, and significantly lower median serum baseline tryptase levels (22.4 vs 28.7 and 45.8 渭g/L; P聽鈮?.009). Moreover, insectISMs鈭?/sup> less frequently presented BM MC aggregates (46%聽vs 70% and 81%; P聽鈮?.001), and they systematically showed MC-restricted KIT mutation.}

Conclusions

ISMs^{鈭?/sup> patients with anaphylaxis triggered exclusively by insects display clinical and laboratory features that are significantly different from other ISM cases, including other ISMs鈭?/sup> and ISMs+ patients, suggesting that they represent a unique subgroup of ISM with a particularly low BM MC burden in the absence of adverse prognostic factors.}