[773] Upper GI Tract Lesions in Familial Adenomatous Polyposis (FAP): Enrichment for Pyloric Gland Adenomas and Other Gastric and Duodenal Neoplasms

Laura D Wood, Safia N Salaria, Michael W Cruise, Elizabeth A Montgomery. Johns Hopkins University, Baltimore, MD

Background: FAP is an autosomal dominant cancer predisposition syndrome caused by germline mutations in the adenomatous polyposis coli (APC) gene. Patients with FAP develop numerous colonic adenomas and invariably develop carcinoma unless a colectomy is performed. In addition, patients with FAP also develop neoplasms of the upper gastrointestinal tract, but these lesions are less well characterized than those in the colon.
Design: All upper gastrointestinal biopsy specimens in patients with FAP were identified at a single institution over a 25 year period. Specimens without neoplasms/polyps or mass lesions were excluded, as were patients with only a single biopsy at our institution. The remaining biopsy specimens were examined histologically to characterize the spectrum of upper gastrointestinal tract neoplasms in patients with FAP.
Results: We identified specimens from 321 endoscopies in 66 patients with FAP. The most common neoplasms were tubular adenomas of the small bowel – we identified 371 tubular adenomas, and at least one tubular adenoma was present in 89% of the included patients. Although tubular adenomas were common in the small bowel, we identified only one case with high grade dysplasia and one case with invasive carcinoma (in patients aged 61 years and 37 years, respectively). Gastric fundic gland polyps were also very common, with 203 total polyps and 65% of patients with at least one fundic gland polyp. Most fundic gland polyps (66%) lacked dysplasia, about 33% had low grade dysplasia and high grade dysplasia was rare (<1%). In addition, several gastric foveolar type gastric adenomas were also identified – 43 adenomas were identified, affecting 23% of patients. Pyloric gland adenomas (PGAs) were also enriched for in FAP patients – 7 PGAs were identified in 4 patients. Although PGAs are uncommon in patients with FAP, they occur at a higher frequency (6%) than in another classic condition with enrichment of PGAs, namely autoimmune gastritis (1%). In spite of the variety of gastric neoplasms reported in this series of FAP patients, only one patient developed invasive carcinoma in the stomach at 39 years.
Conclusions: Although patients with FAP frequently develop neoplasms in the upper gastrointestinal tract, current screening procedures with removal of suspicious lesions prevent the vast majority of carcinomas in these patients. In addition to fundic gland polyps and gastric foveolar type gastric adenomas, patients with FAP are also predisposed to pyloric gland adenomas, a novel finding in this study of upper gastrointestinal tract lesions in FAP.
Category: Gastrointestinal

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 121, Monday Morning


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