Gastrointestinal tract-derived pulse granulomata: clues to an underrecognized pseudotumor.

Pulse granulomata (PG) in the lung and oral pathology literature are presumed due to food (pulse) introduced by mucosal injury. Herein, we report the largest series of PG in the gastrointestinal tract (GIT): 22 resections were prospectively collected from 17 patients (8 men, range=28 to 85 y). All patients had a history of intestinal injury/disease: diverticulitis, fistula, adenocarcinoma, perforation, ulcerative colitis, appendicitis, anastomotic site leak, and/or stent leak. Nine of 22 specimens were designated "masses"; most of these were clinically concerning for neoplasia. Sites of involvement included the small and large intestine, appendix, liver, gallbladder, mesentery, omentum, peritoneum, cervix, ovary, and skin. PG were typically nodular (21/22) and multifocal (15/22); most involved the external surface of the bowel (20/22), and they ranged in size from 1.5 to 100 mm. Histologically, they contained variable amounts of hyaline ribbons and rings, inflammation, foreign body giant cells, calcifications, and food; larger lesions displayed circumferential stellate fibrosis (12/22). We describe 3 morphologic variants: hyaline predominant (mimicking amyloid), cellular predominant (mimicking spindle cell neoplasms), and sclerosing mesenteritis-like. All patients are alive and well at the time of follow-up. Histologically processed legumes showed similar structures as those identified in PG, providing support for an entrapped food origin. In summary, we detail important clinicopathologic clues, describe the PG morphologic spectrum, and demonstrate how to distinguish PG from their mimics. Although PG can present as clinically concerning masses, we conclude that they are pseudotumors arising secondary to entrapped food introduced through mucosal trauma, similar to their lung and oral counterparts.