A Case of Descending Colon Cancer with Intra-abdominal Hemorrhage due to Segmental Arterial Mediolysis Requiring Emergency Surgery

Abstract

The patient was a 68-year-old man who presented to the gastroenterology department of our hospital with nausea and lower abdominal pain. Colonoscopy showed descending colon cancer, and though an attempt was made to relieve the obstruction with a stent, placement proved difficult. He was therefore referred to our department the same day for a colostomy. That evening, his lower abdominal pain worsened, and his vital signs indicated shock. Contrast-enhanced computed tomography (CT) showed intra-abdominal bleeding due to the rupture of a pseudoaneurysm in the middle colic artery, leading to emergency surgery. During surgery, a large hematoma and bloody ascites were found in the abdominal cavity. Partial resection of the transverse colon was performed. Though simultaneous resection of the descending colon cancer was considered, lesions suspicious of splenic infiltration and peritoneal dissemination were observed, and only the colostomy was completed. Pathology showed partial defects in the vascular walls of the medium-sized mesenteric arteries and vacuolar degeneration of the smooth muscle, leading to a diagnosis of segmental arterial mediolysis (SAM). SAM associated with gastrointestinal cancer is rare, and this report includes a review of the literature.