A type-4 sigmoid colon carcinoma difficult to differentiate from diverticulitis

Abstract

A 67-year-old man was seen for lower abdominal pain and hospitalized. Pressure pain and a palpable mass were present in the lower left abdomen, and hematology tests showed severe inflammatory signs, with a leukocyte count of 20,600 cells/μl, and C-reactive protein at 14 mg/dl. Abdominal CT showed multiple sigmoid colon diverticula, wall thickening, and increased concentration of adipose tissue in the surrounding area, so a diagnosis of diverticulitis was made, and the patient was admitted to the hospital as an emergency case. Endoscopic examination of the large intestine showed partial circumferential stenosis and edematous changes and reddening on the mucosal surface in the sigmoid colon, and the endoscope could not pass through this region. Biopsy showed no signs of malignancy. Conservative treatment was carried out, but abdominal pain and inflammatory signs recurred, so sigmoidectomy was performed. Histological tests showed type-4 sigmoid colon carcinoma (tub1, SS, and N2). In particular, welldifferentiated adenocarcinoma extended and caused colonic stenosis with marked inflammatory cell infiltration and fibrosis without cancer lymphopathy, so it was thought to be the inflammatory type. A further colectomy was carried out to perform lymph node dissection, and 12 courses of mFOLFOX6 were administered as postoperative adjuvant chemotherapy, followed by monitoring with no signs of recurrence for 18 months. Recurrent diverticulitis should be considered in the differential diagnosis of type-4 colorectal carcinoma.