Demographics, Types of Patient-reported Allergic Diseases and Anaphylaxis in Mastocytosis: A single center U.S. experience.

Background: Patients with mastocytosis are at increased risk of anaphylaxis. Idiopathic anaphylaxis and venom induced allergy are commonly reported in mastocytosis, however the incidence of other allergies has been less well studied.

Objective: We sought to characterize the true prevalence of allergic disease including food, venom, contrast, and drug allergy compared to the number of patients that simply avoid potential triggers. We also gathered demographic information.

Methods: We performed a retrospective study of 259 consecutive pediatric and adult patients with a confirmed diagnosis of either cutaneous or systemic mastocytosis who received care through the University of Michigan Health system from 1/1/2018 to 3/17/2021.

Results: Mastocytosis was more prevalent in non-Hispanic white population. As compared to the general population, patients had similar rates of atopy and allergies with a slight increase in reported asthma prevalence. Overall prevalence of anaphylaxis was 28% and the great majority occurred in SM, with most common trigger being hymenoptera venoms. Most patients reported drug allergies preemptively in order to avoid exposure, particularly to NSAIDs. We also saw an increase in contrast-induced anaphylaxis compared to prior literature, and a lower prevalence of venom allergy as compared to European cohorts.

Conclusion: Our study characterizes the rate of common atopic conditions as well as allergies in a large cohort of patients with mastocytosis in the US. Anaphylaxis in CM is rare. Hymenoptera venoms were the most common trigger for anaphylaxis while drug allergies were overreported preemptively in order to avoid potential exposures due to concern for having a reaction.