Pyloric Gland Adenoma: Uncommon or Unrecognized?

Abstract

Gastric pyloric gland adenomas (PGAs) are rare epithelial polyps that are found more commonly in autoimmune atrophic gastritis and familial adenomatous polyposis (FAP). PGA are clinically significant because they are neoplasms with malignant potential rather than a hyperplasia of metaplastic glands. We report a case of invasive adenocarcinoma arising from PGA with high grade dysplasia in a patient without history of pernicious anemia or FAP. An 80 year old female with a history of intermittent episodes of severe fecal urgency underwent CAT scan of the abdomen and pelvis for evaluation of possible GI tumors, which revealed polypoid irregular mass in the cardia measuring 3.6 x 3.4 cm. Subsequently, EGD confirmed the presence of 3cm circumferential polypoid mass at the cardia. Biopsy of the mass revealed pyloric gland adenoma with high grade dysplasia. Esophago-gastrectomy was performed and the final pathology results demonstrated well to moderately differentiated invasive adenocarcinoma, arising in low and high grade dysplasia, invading mucosa. Immunostains showed intact expression of mismatch repair proteins (MLH1, MSH2, MSH6 and PMS2) on tumor cells. Atrophic gastritis with intestinal metaplasia negative for H pylori was present. Tumor stage (AJCC 20010): pT1aN0 Gastric PGA have been shown to arise in chronically damaged mucosa. PGA was first mentioned in the 1990 WHO classification and was not fully described until 2003 by German investigator Vieth et al reported 90 such lesions encountered in the stomach, duodenum, bile duct, and gallbladder. This neoplasm has not been well recognized as a distinct entity in the US literature, until Chen ZM et al., reported the largest US series of 41 PGA in 2009. The greatest diagnostic challenge with PGAs is distinguishing them from foveolar-type adenomas. PGAs are probably more common than the literature suggests, have a characteristic histologic appearance, and have the capacity to evolve into infiltrating adenocarcinomas. In these two largest series, gastric PGAs have frequent association with adenocarcinoma, ranging from 12% to 30% of cases.2645_A Figure 1. Endoscopic image2645_B Figure 2. Intraoperative image2645_C Figure 3. HistologyWe present this case of invasive adenocarcinoma arising from pyloric gland adenoma with high grade dysplasia in a patient with atrophic gastritis. PGA were recognized years ago by European and Japanese pathologist whereas North American pathologists learned to diagnose them more recently, therefore these clinically significant lesions may be underrecognized and underreported.