Mo1562 Inflammatory Fibroid Polyp of the Stomach: Clinical and Pathologic Characteristics of 28 Consecutive Cases Seen Over a 44-Month Period

Abstract

Purpose: Gastric adenomas of intestinal differentiation are much more common than the more recently described adenomas of gastric differentiation. The purpose of this study was to compare the incidence and age at which adenomas of gastric phenotype occur compared to the more common intestinal type gastric adenomas. Methods: We used a large national pathology database of patients who undergo upper endoscopy at community-based surgery centers to determine the relative prevalence and associations of gastric foveolar adenomas, pyloric gland adenomas, and intestinal type adenomas. We extracted pertinent demographic, clinical, endoscopic, and histopathologic information from all patients who had a diagnosis of one of these three types of gastric polyps between 1/1/2008 and 11/1/2011. Frequency distributions and simple odd ratios were used to determine the significance of the associations. Results: From a total of 640,991 patients who underwent upper endoscopy (median age 58 years; 59.8% women), we identified a total of 549 with a diagnosis of gastric adenoma. Of those 443 (81%) were intestinal type, 77 (14%) were foveolar adenomas, and 29 (5%) were pyloric gland adenomas. In each case, the diagnosis was made on H&E stain. Intestinal-type gastric adenomas resembled colonic adenomas with loss of mucin, enlarged and elongated pseudostratified nuclei, and typically associated intestinal metaplasia with Paneth cells. Pyloric gland adenomas were composed of densely packed pyloric glands lined by cuboidal or short columnar cells, and a, typically, unremarkable surface epithelium. Foveolar adenomas featured a surface-predominant villous or papillary architecture with larger than normal foveolar cells and elongated nuclei. There was no significant difference between the median age of the different type of polyps (72 years for intestinal type, 77 for foveolar, and 73 for pyloric gland). There was, however, a significant predominance of women (86.2%) among pyloric gland adenomas (OR=3.86, p<0.01), but not among foveolar adenomas (55.8% women). A small fraction of the study group was known to have FAP (3.4% of intestinaltype adenomas, 2.6% of foveolar adenomas, and none of pyloric gland adenomas). Conclusion: Among a large nationwide population with endoscopy and biopsy for gastric adenomas, intestinal-type adenomas predominate, but almost 20% are of gastric phenotype and may be under-recognized. Our data also reaffirms previous studies that demonstrate a female predominance among pyloric gland adenomas.