Carcinoid and Inflammatory Bowel Disease: Coincidence or Complication?

Abstract

Purpose: It is well established that long-standing 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 tumors diagnosed in IBD patients admitted to our institution within days of each other. Case 1 involves a 44 year-old male with a 20-year history of Crohn's. After 8 years of abdominal pain, he developed a small bowel perforation requiring emergency laparotomy with ileocecal resection. Surgical pathology revealed a well-differentiated T2N1M0 carcinoid tumor measuring 12 mm. The remaining excised small bowel had extensive involvement with Crohn's disease with a fistula tract extending into the region of the appendix associated with an abscess and serositis. 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 began treatment with IM octreotide but continued to have high-output fistulae and 10 years after his initial surgery, he underwent resection of several fistulae and a previously placed jejunal-colic anastomosis. Small bowel pathology showed evidence of now metastatic, well differentiated neuroendocrine tumor. Case 2 involves a 49 year-old 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 less than 4mm. Further radiographic investigation and repeat colonoscopy failed to reveal a primary carcinoid. Discussion: 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. The two cases presented had active inflammation at the time the diagnosis of carcinoid tumor was made. They differ in the location of the carcinoid - the patient with Crohn's had evidence of carcinoid in the distal ileum and jejunum, both areas without inflammation, while the patient with ulcerative colitis had carcinoid tumor identified in a random distal colon biopsy. Both cases support the hypothesis that there may be an association between carcinoid and IBD, but Case 1 suggests carcinoids can arise in areas without chronic mucosal inflammation.