A 68-year-old woman visited our hospital because of a positive fecal occult blood test. Colonoscopy revealed a type 2 tumor in the ascending colon, and a whitish flat lesion that had a white node in the center of the transverse colon. Magnifying endoscopy showed Vi pit pattern at the white node, and an open II type surrounding the flat lesion. Therefore, we diagnosed this patient as having cancer of both the ascending and transverse colon. We performed Endoscopic Submucosal Dissection (ESD) for the transverse colon cancer, and a right hemicolectomy for the ascending colon cancer. On histology, the ascending colon tumor and the transverse colon tumor were diagnosed as papillary well-differentiated adenocarcinoma, and well-differentiated adenocarcinoma in serrated adenoma, respectively.
The ascending colon cancer had no microsatellite instability (MSI) and BRAF mutation, but the transverse colon cancer had MSI-high and BRAF mutation. These findings suggest that each cancer had different pathways of colon carcinogenesis.
