Colonic Adenocarcinoma Arising from Gastric Heterotopia: A Case Study
A 70-year-old female patient was hospitalized because of known cholangitis. She had previously undergone cholecystectomy because of the cholelithiasis. Physical examination revealed tenderness of the lower quadrants of the abdomen. As part of the clinical work-up, the patient underwent an abdominal computed tomography, which demonstrated colonic distension and small bowel ileus with focal narrowing and obstruction of the transverse colon (). Mechanical obstructive ileus was suspected, and a colonoscopy revealed luminal erosion and stricture of the transverse colon. Microscopic examination of multiple blind biopsies showed erosion and vascular congestion with no evidence of malignancy. A whole body scan to evaluate the presence of metastatic lesions did not show any abnormal fluorodeoxyglucose uptake. The patient was diagnosed with colonic malignancy, and right hemicolectomy was performed.\nOn gross examination, the resected specimen displayed infiltrative submucosal lesions that involved the whole circumference and resulted in colonic stricture (). Histologically, the colonic mucosa was intact except for focal erosion, and the muscular layer was markedly hypertrophied at the stricture site. Further microscopic examination revealed that a benign glandular structure of gastric origin invaded the erosive colonic mucosa. These glands showed a downward growth pattern toward the submucosa and the muscular layer, gastric differentiation, and focal cystic dilatation (). Additionally, we identified an adenocarcinoma that originated in the heterotopic gastric glands in the submucosa and muscular layers. The adenocarcinoma foci were composed of glands as well as isolated tumor cells and clusters with focal mucin production and were moderately to poorly differentiated (). The tumor was distributed through the colonic wall and pericolic soft tissue. Immunohistochemically, both the heterotopic glands and adenocarcinoma showed positive results for cytokeratin (CK) 7 and MUC5AC and were negative for CK20, CDX2, and MUC2 (, ). On the basis of these findings, heterotopic gastric mucosa in the transverse colon and development of invasive adenocarcinoma were diagnosed and staged at pT3, pN1b (2/43), pMx according to the 7th edition of the Cancer Staging Manual of the American Joint Committee on Cancer.