sigmoid colon perforation during colonoscopy in a case of carcinoid tumor

Background: carcinoids tumors are slow-growing tumors which originate mainly from the small intestine and can produce biogenic peptides and amines. these products could cause carcinoid syndrome, and also, fibrosis in the peritoneum and mesentery. case report: a 50-year-old man complaining of lower limb edema, ascites, and weight loss presented for evaluation. ct scan of the abdomen and pelvis revealed liver enlargement and the increased thickness of cecum and terminal ileum. the patient consented to an exploratory colonoscopy, which led to laparotomy resulting from sigmoid colon perforation. large retroperitoneal fibrosis developing with colon and mesentery of sigmoid was found during surgery. hepatomegaly with microscopic tumoral infiltration of the liver was observed and diagnosis of metastatic carcinoma in the liver was confirmed by pathological examination. conclusion: the most common sites of primary carcinoid tumors are appendix, ileum, and cecum. one of the less common manifestations of carcinoid tumors is fibrotic reactions around or beyond the tumor that in the reported patient, there was a very extensive fibrosis in the mesentery and peritoneum and serosa covering the colon and intestines, which presented with edema of the lower extremities because of the pressure on the ivc and with perforation of the colon during colonoscopy.