Low Grade Pre-malignant Lesion of Pancreatic Rest in Stomach, Surveillance a Dilemma

Abstract

INTRODUCTION: Pancreatic intraepithelial lesions (PanIN) are premalignant lesions of pancreatic ductal adenocarcinoma (PDA). PanIN and PDA found in ectopic gastric pancreatic rest tissue are extremely rare, with only two cases of low-grade PanIN in ectopic gastric ectopic pancreatic tissue reported. In this case report, we present a case of PanIN in gastric ectopic pancreatic tissue found after lesion removal by endoscopic mucosal resection (EMR). CASE REPORT: A 47-year-old female with no significant history underwent an upper endoscopy for abdominal pain. Upper endoscopy revealed gastritis in the stomach and a 1 cm subepithelial lesion with central umbilication in the gastric antrum (figure 1). Endoscopic ultrasound examination revealed that the lesion was arising and limited to only the submucosa. EMR was performed to remove the lesion en bloc (figure 1). Pathological examination revealed gastric heterotopic pancreatic tissue and focal pancreatic intraepithelial neoplasia 1A (figure 2). Follow-up surveillance endoscopy performed at 6 months revealed no evidence of recurrence (figure 3).Figure: Endoscopic image showing (Left) A 1 cm submucosal polyp with central umbilication in the antrum. (Middle) Post en-block removal of polyp by endoscopic mucosal resection technique. (Right) Lesion closed with 2 clips.Figure: Histopathologic examination of haematoxylin and eosin stained pancreatic rest tissue specimen under x400 shows that pancreatic duct is lined by a single layer of epithelium with abundant apical mucinous cytoplasm and basal nuclei that lack atypia consistent with Pancreatic Intraepithelial Neoplasia 1A.Figure: Endoscopic image showing a scar tissue in the antrum from prior intervention with no residual pancreatic rest tissue.DISCUSSION: PanIN refers to a small intraductal noninvasive lesion formed by metaplasia and proliferation of ductal epithelium. It is classified by dysplasia severity—PanIN 1 and 2 are low grade, and PanIN 3 is high grade. In orthotopic pancreas, PanIN 3 is known as carcinoma-in-situ. Conversely, PanIN 1 and 2 tumors grow slowly, might take up to 12 years to transition into PanIN 3 and even longer to change to PDA. These results can be extrapolated to pancreatic rest tissue due to similar mutations. Presently, asymptomatic pancreatic rest is monitored, while symptomatic cases—or those suspicious of malignancy on ultrasound—are resected using endoscopic techniques or surgical resection. There are no guidelines for endoscopic surveillance and therapy of these asymptomatic, premalignant and malignant gastric ectopic pancreatic rest lesions. In this case we highlight a very rare incidence of a low-grade premalignant lesion within gastric ectopic pancreatic rest removed by endoscopic resection. Further research is necessary to better define strategies for endoscopic surveillance and therapy of asymptomatic gastric ectopic pancreatic rest given the potentiality of these lesions to be premalignant and transform into malignant lesions that carry a poor prognosis.