A Case of Rectosigmoid Colon Cancer with Tumor Thrombus in the Inferior Mesenteric Vein

Abstract

The patient was a 65-year-old man. In October 2020, he visited a nearby clinic doctor with a chief complaint of bloody stools. Colonoscopy revealed a mass lesion in the rectosigmoid colon, and he was referred to the department of internal medicine at our hospital in the same month. After close examination, he was diagnosed with rectosigmoid colon cancer and was referred to general surgery for the surgical procedure. Preoperative CT showed a 5 cm venous tumor thrombus or clot formation in the inferior mesenteric vein continuous from the primary lesion. No metastasis was found in distant organs, and preoperative evaluation revealed stage IIIB cancer based on the UICC TNM Classification System (8th edition). In November, he underwent laparoscope-assisted colectomy with D3 lymph node dissection. The postoperative course was uneventful, and he was discharged from the hospital. Postoperative pathological examination also revealed stage IIIB cancer, and the lesion in the inferior mesenteric vein, pointed out preoperatively, was diagnosed as a tumor thrombus. Currently, postoperative adjuvant chemotherapy with mFOLFOX6 is being performed, and no recurrence has been observed to date.