A case of rapidly progressing and poorly differentiated Ip‐type early‐stage colorectal adenocarcinoma

Abstract

A 36‐year‐old woman visited our hospital with a chief complaint of bleeding during defecation. Colonoscopy revealed a 20‐mm pedunculated polyp in the sigmoid colon, which was en bloc resected under endoscopy. The histopathological diagnosis was adenoma cancer with a depth of invasion indicating mucosal cancer, no lymphovascular invasion, and negative at the resection margin. The poorly differentiated adenocarcinoma component comprised approximately 5% of the tumor. Although there were no recurrence signs in the computed tomography scans obtained 4 months post polypectomy, the patient experienced aggressive lower back pain at 6 months post polypectomy. Local recurrence, peritoneal dissemination, and liver metastasis were confirmed. Finally, the patient died following a rapid and aggressive deterioration of her general condition. Histological examination of the local recurrence revealed a poorly differentiated adenocarcinoma (por2), with immunostaining revealing a high Ki67 positivity rate of 95%. Moreover, the poorly differentiated adenocarcinoma region of the resected polyp had a Ki67 positivity rate of 90%, which suggested that they were the same tumors. These findings suggested that the recurrence could have occurred through implantation.

A call for standardized reporting of early-onset colorectal peritoneal metastases

“…While these genes appear to be associated with CPM incidence, causality cannot be determined. A high positivity rate of Ki67 in primary colorectal tumor tissue may also be related to cancer recurrence including metachronous CPM (Tsubomoto et al , 2023).…”