Heterotopic Pancreas of the Gastrointestinal Tract and Associated Precursor and Cancerous Lesions

Abstract

Heterotopic pancreas (HP) can be detected by accompanying symptoms or incidentally during gastrointestinal (GI) tract tumor resection. We compared clinicopathologic features among 165 resected HPs (57 gastric [35%], 56 duodenal [34%], 30 omental [18%], and 22 jejunal [13%]). Symptomatic HPs (79/135 GI tract wall HPs, 59%) were larger (P=0.05), more common in younger patients and in a gastric location (both P<0.001), and more frequently associated with lymphoid cuffs (P=0.03) than incidentally found HPs. Gastric/jejunal HPs were more frequently symptomatic (P<0.001), deeply located (P=0.03), and associated with lymphoid cuffs (P=0.008) and pancreatic intraepithelial neoplasia/intraductal papillary mucinous neoplasms (PanIN/IPMN; P=0.001) than duodenal HPs. HP was frequently associated with acinar-ductal metaplasias (117/135 GI tract wall HPs, 87%) and PanINs/IPMNs (68/135, 50%); those with PanINs/IPMNs were larger (P<0.001), more frequently located in stomach (P=0.001), had deeper wall involvement (P=0.03), and more often showed infiltrative growth (P<0.001) and lymphoid cuffs (P=0.02). Four HPs containing PanINs abutted adenocarcinomas, all expressing wild-type KRAS and intact SMAD4/DPC4 expression. Thus, symptomatic HP is associated with younger age, larger size, gastric location, and lymphoid cuffs. HPs containing PanINs/IPMNs (usually low grade) are larger and more common in stomach, have deeper wall location, and show infiltrative growth and lymphoid cuffs. Adenocarcinomas are rarely observed adjacent to HPs with PanINs/IPMNs. KRAS mutational and SMAD4/DPC4 immunohistochemical studies can discriminate between adenocarcinoma derived from HP and concurrent adenocarcinoma with HP.

Pancreatic intraepithelial neoplasia in heterotopic pancreas: incidentally diagnosed on endoscopic mucosal resection of a duodenal polyp

“…These PanINs are histologically well-defined precursors and have been recognised in the heterotopic pancreatic tissue as well. They are larger, more common in stomach, have deeper wall location, and show infiltrative growth and lymphoid cuffs 6. PanIN-1A and PanIN-1B (low-grade PanIN) have a flat and papillary structure, but lack nuclear abnormality.…”

Duodenal Epithelial Polyps: A Clinicopathologic Review

“…It is most common in the duodenum but can also be found in the jejunum, liver, biliary tract, and omentum. 22 The endoscopic appearance of pancreatic heterotopia is that of a small nondescriptive nodule covered by normal duodenal mucosa, often with central umbilication corresponding to the opening of the main duct. Such lesions when large may become symptomatic, most commonly presenting with abdominal pain, obstruction, intussusception, stricture, or bleeding.…”

“…Clinical Significance and Treatment.-Pancreatic heterotopia can undergo pathologic changes similar to those observed in the pancreas such as pancreatitis, pseudocyst, abscess formation, and rarely, dysplasia and malignancy. 22 Endoscopic or surgical resection is the treatment of choice when they become large and symptomatic or show evidence of dysplastic features.…”

Páncreas ectópico, diagnóstico diferencial de lesión gástrica subepitelial: Reporte de caso y enfrentamiento inicial

“…Se define como la presencia de tejido pancreático ubicado a distancia del órgano principal, sin relación anatómica o vascular. Se ubica habitualmente en el estómago (25-38%), duodeno (17-36%) y yeyuno proximal (15-21,7%) 6 , pudiendo estar presente en cualquier localización intraabdominal 7 .…”