Utility of quantifying mast cells in gastrointestinal biopsies in patients with suspected mast cell activation...

Patients often present to the Allergist/Immunologist with concerns for mast cell activation disorder with associated gastrointestinal symptoms (MCAD-GI). Currently, there is limited evidence supporting diagnostic utility of staining for mast cells (MCs) on GI biopsy samples.

To determine whether patients presenting with suspected MCAD-GI had increased MC density on GI biopsies compared with an asymptomatic cohort and whether MC densities correlated with GI symptoms or improvement from MC-targeted medications.

A retrospective chart review was performed to identify patients with MC disorders who had undergone endoscopies for biopsy of the duodenum and/or colon. Information regarding comorbidities, GI symptoms, and response to medications targeting MC activation and mediators was extracted. MC staining (tryptase and CD117) was performed and analyzed.

A total of 44 patients were identified, of which 39 met inclusion/exclusion criteria. Patients were predominantly female, and the most common GI symptom was diarrhea. Duodenal and colonic MC densities were increased compared with asymptomatic control subjects. There was no difference in specific GI symptoms or clinical response to MC-targeted therapies between patients with "high" and "low" MC density in either the duodenum or colon.

Patients with suspected MCAD presenting with GI symptoms have higher GI MC counts compared with an asymptomatic cohort; however, no clear cutoff is identified, and local mastocytosis is not associated with GI symptoms or response to MC-targeted therapies. Future studies should determine whether MC subsets or their activation state are better markers for understanding the role of MCs in patients who present with presumed MCAD-GI.