Intramural cancer recurrence in the rectum after curative surgery for proximal sigmoid colon cancer: a case report

Abstract

Background:Intramural metastasis distant from the primary tumor is rare in colorectal cancer. Here, we present a notably rare case of asynchronous intramural recurrence in the rectum after curative surgery for proximal sigmoid colon cancer. To the best of our knowledge, our paper is the first case report of this type of recurrence.Case presentation:A 44-year-old man underwent curative sigmoidectomy for proximal sigmoid colon cancer with tubular adenocarcinomas. The pathological diagnosis was T3N0M0, Stage IIA, according to the 8th Union for International Cancer Control classification. Moderate venous invasion was observed, and all resection margins were negative, including sufficient proximal and distal margins from the tumor.After 15 months, the tumor marker level had increased, and positron emission tomography-computed tomography (PET-CT) revealed abnormal fluorodeoxyglucose uptake in the rectum. Colonoscopy revealed a submucosal tumor (SMT)-like lesion in the upper rectum, and biopsy revealed a tubular adenocarcinoma. We performed curative low anterior resection based on a diagnosis of an atypical primary cancer or a rare case of intramural recurrence. We chose tumor-specific mesorectal excision (TSME) with a distal margin of 3 cm from the tumor. The SMT-like tumor was located approximately 20 cm from the initial sigmoid colon anastomosis (i.e., at least 20 cm distal to the initial sigmoid colon cancer), and pathological findings revealed cancer cells with the same features as the initial sigmoid colon cancer, only in the intestinal wall but not in the mucosa. Therefore, the recurrence was determined to be intramural. Severe venous invasion was also observed, and all resection margins were negative.After 24 months, lung recurrence and local recurrence, which may have involved the lymph nodes in the preserved mesorectum after TSME at the bottom of the pelvis, was detected on PET-CT. We started systemic chemotherapy and stable disease was achieved.Conclusions:This report presented a rare case of asynchronous intramural recurrence in the rectum after curative surgery for proximal sigmoid colon cancer. The discussion regarding the etiology, diagnosis, and optimal surgical procedure to achieve local control for rare intramural recurrence in colorectal cancer should provide valuable information in the clinical setting.