Perforated colorectal cancer: an important differential diagnosis in all presumed diverticular abscesses.

Dear Editor, Colorectal cancer (CRC) is the most common cancer in Singapore1 and is also on an increasing trend.2 Common presenting symptoms of CRC include abdominal pain, change in bowel habits, per rectal bleeding, anaemia and weight loss.3 A less frequent presentation is perforation and abscess formation, which is usually intraperitoneal but may occasionally be located in extraperitoneal spaces. With contained perforation and abscess formation, the clinical picture can closely resemble complicated diverticulitis, whether on clinical examination or on radiological imaging such as Computed Tomography (CT) scans. Patients typically present with fever, abdominal pain and leukocytosis, and CT scans show a pericolic or intra-abdominal abscess. It is thus important to consider the diagnosis of colonic carcinoma in patients who present with such a clinical picture. We present 3 cases of carcinoma of the colon presenting as a pericolic abscess over a period of 2 months—initially diagnosed as a diverticular abscess—for which diagnosis of carcinoma was made intraoperatively.