Heterotopic Pancreatic Epithelium in the Colon

Abstract

Purpose: Heterotopic pancreatic tissue is frequently found in stomach and small intestine. However, endoscopists do not expect to find pancreatic tissue in the colon. A 62-year-old man underwent colonoscopy for persistent left lower quadrant abdominal pain and hematochezia for several months. Colonoscopy revealed three small sessile adenomatous polyps in the transverse colon, hepatic flexure and sigmoid colon; all were completely resected. In addition, a fourth 1.1 cm villous, friable and pedunculated polyp was completely removed from the sigmoid colon using snare cautery polypectomy. Histopathologic evaluation of hematoxylin and eosin-stained slides revealed ectopic pancreatic columnar epithelium in this fourth polyp. Cells did not have dysplastic features such as hyperchromatic, crowded nuclei. Immunohistochemical stains confirmed the diagnosis of ectopic pancreatic epithelium with positive results for cytokeratin 7 (CK7) and cytokeratin 20 (CK20); these features distinguish ectopic pancreatic epithelial cells from colonic epithelium which would be positive for CK20 but are always negative for CK7. The prevalence of heterotropic pancreatic epithelium in the colon is not known. In a study of 212 cases with heterotropic pancreatic tissue from the Mayo Clinic, no colonic involvement was reported. In most instances, ectopic pancreatic tissue is asymptomatic clinically and manifests as an incidental submucosal nodule found during upper GI endoscopy. However, in this case, a friable polyp containing pancreatic epithelium resulted in rectal bleeding and abdominal pain which resolved with polypectomy. This is the first case of heterotopic pancreatic tissue found in the sigmoid colon.Figure: Heterotopic polypoid pancreatic epithelium in the sigmoid colon.Figure: Heterotopic pancreatic epithelium; hematoxylin and eosin stain.