Giant sigmoid diverticulum with coexisting metastatic rectal carcinoma: a case report

INTRODUCTION Giant diverticulum of the colon is a rare but clinically significant condition, usually regarded as a complication of an already existing colonic diverticular disease. This is the first report of a giant diverticulum of the colon with a co-existing rectal carcinoma. CASE PRESENTATION We report a case of a 66-year-old Caucasian woman who presented with lower abdominal pain, chronic constipation and abdominal swelling. Preoperative abdominal computed tomography revealed a giant diverticulum of the colon with a coexisting rectal carcinoma and pulmonary metastasis revealed on a further thoracic computed tomography. An en bloc anterior resection of the rectum along with sigmoid colectomy, partial hysterectomy and right salpingoophorectomy was subsequently performed due to extensive adhesions. CONCLUSION This report shows that the presence of a co-existing distal colorectal cancer can potentially lead to progressive development of a colonic diverticulum to become a giant diverticulum by increasing colonic intra-luminal pressure and through the ball-valve mechanism. This may be of interest to practising surgeons and surgical trainees.