Extraluminal Colonic Adenocarcinoma Directly Invading the Left Kidney: A Rare Case of Direct Invasion.

The most common distant metastatic sites of colorectal cancer (CRC) are the liver, lungs, and peritoneum. Renal involvement from colon cancer is rare and, when present, usually occurs via hematogenous spread. Direct invasion of the kidney by a primary colonic adenocarcinoma is exceptionally uncommon, with very few cases reported in the literature. We report the case of a 65-year-old woman who presented with vomiting, obstipation, and diffuse abdominal pain due to bowel obstruction. Computed tomography (CT) of the abdomen demonstrated soft tissue thickening around the mid-descending colon, partial luminal obstruction, proximal bowel dilatation with air-fluid levels, marked cecal dilatation, and suspected direct contact with the left kidney. Emergency rectosigmoidoscopy revealed an obstructing mass in the descending colon. The patient subsequently underwent urgent exploratory laparotomy, during which marked colonic dilatation with impending cecal rupture was identified. Subtotal colectomy with end ileostomy was performed. Intraoperatively, the tumor was also found to infiltrate the left kidney, and left nephrectomy was carried out. Histopathological examination established the diagnosis of moderately differentiated colonic adenocarcinoma measuring 6.6 cm, with direct invasion into Gerota's fascia, the perirenal adipose tissue, and the renal parenchyma. This case highlights an exceptionally rare pattern of locally advanced colon cancer and underscores the need to consider adjacent organ invasion in patients presenting with obstructing left-sided colonic tumors.