Carcinoid Tumors and Inflammatory Bowel Disease: A Possible Association

Abstract

It is well established that longstanding inflammatory bowel disease (IBD) is associated with an increased risk of small bowel and colorectal adenocarcinoma. The association of neuroendocrine tumors and IBD is less well understood. We report 2 cases of neuroendocrine tumor diagnosed in IBD patients admitted to our institution within days of each other and a third case of a patient with a previous diagnosis of neuroendocrine tumor referred to our institution for consultation. Case 1 involves a 44 year-old Caucasian male with a 20-year history of Crohn's. After 8 years of abdominal pain, he developed a small bowel perforation and underwent emergency laparotomy with ileocecal resection. Surgical pathology revealed a well-differentiated T2N1M0 carcinoid tumor measuring 12 mm within the distal ileum without associated inflammation. The remaining excised small bowel had extensive involvement with Crohn's disease with a fistula tract extending into the appendix associated with an abscess. Post-operatively, his course was complicated by recurrent fistula formation and resultant malabsorption. Eight years after the initial resection, he had a positive Octreotide scan but no further radiographic evidence of carcinoid recurrence. He was treated with IM Octreotide but continued to have high-output fistulae and, 2 years later, underwent resection of several fistulae. Small bowel pathology showed evidence of now metastatic, well differentiated neuroendocrine tumor. Case 2 involves a 49 year-old Caucasian female with a 35-year history of untreated ulcerative colitis, admitted with bloody stools and abdominal pain. Biopsies obtained during diagnostic flexible sigmoidoscopy showed severe colitis and an incidental, well-differentiated neuroendocrine tumor measuring 4 mm. Further radiographic investigation including octreotide scan and repeat colonoscopy failed to reveal a primary carcinoid. Case 3 involves a 62 year-old Caucasian female who was referred to our institution for the management of ileocolonic Crohn's disease diagnosed 35 years ago. She experienced symptoms of rectal bleeding and abdominal pain for 4 years prior to diagnosis and by the time she sought medical attention, she required an emergency laparoscopy with ileocecectomy for massive hemorrhage. The pathology specimen showed an early carcinoid tumor within the terminal ileum. She was followed for 10 years afterwards without any evidence of tumor recurrence. Discussion(s): Gastrointestinal carcinoid tumors are rare, and the concomitant diagnosis of carcinoid and IBD is even rarer. It has been debated whether the incidence of carcinoid tumors is actually increased in patients with IBD or if there are simply more incidental carcinoids diagnosed in IBD patients who are more likely to require surgery for a complication of the intestinal inflammation. All three cases presented had concurrent active inflammation when the carcinoid tumor was discovered. They differ in the location of the carcinoid - Case 1 had evidence of carcinoid in an area without inflammation, while Case 2 had carcinoid tumor identified amongst severe inflammation in the rectum and Case 3 had carcinoid tumor in an inflamed terminal ileum. These cases support the hypothesis that there may be an association between carcinoid and IBD, but Case 1 suggests that carcinoids can also arise in areas without chronic mucosal inflammation.