Mast Cell Disorders of the Gastrointestinal Tract: Clarity out of Chaos.

Pathologists are increasingly asked to evaluate mast cell infiltrates in the gastrointestinal tract when there is clinical concern for systemic mastocytosis or a variety of functional disorders, including irritable bowel syndrome and mast cell activation syndrome. Neoplastic mast cells have established quantitative, morphologic, and immunohistochemical features that facilitate their identification in gastrointestinal mucosal biopsies. Specific qualitative and quantitative findings are lacking for inflammatory mast cell-mediated disorders. This review covers histopathologic features of mast cell disorders that affect the gastrointestinal tract and offers practical guidance for their assessment in mucosal biopsies.