NEUROENDOCRINE NEOPLASMS ARISING IN INFLAMMATORY BOWEL-DISEASE - A REPORT OF 14 CASES

Inflammatory bowel disease (IBD), particularly ulcerative colitis (UC) , is a premalignant condition, because these patients are at increased risk of adenocarcinoma. Neuroendocrine neoplasms (NENs) have rarely b een described in this setting. We evaluated 14 cases of NEN arising in a setting of IBD. All of the tumors arose in areas involved by IBD, a nd all showed immunohistochemical or ultrastructural evidence of neuro endocrine differentiation. The cohort included seven men and seven wom en (range, 28-71 yr; median, 43 yr). Eight patients had Crohn's diseas e (CD), and six had UC. Duration of disease ranged from 4 months to 50 years (median, 15 yr), with one of unknown duration. Of the eight pat ients with CD, five had ileocolitis, one had ileitis, one had colitis, and in one case, the extent of disease was unknown. Of the six patien ts with UC, four had extensive UC, one had left-sided UC, and the exte nt of UC tvas unknown in one case. Reasons for surgery included CD com plications (five patients), refractory disease (three patients), dyspl asia/carcinoma (five patients), and incontinence (one patient). The NE Ns were well differentiated in 11 cases and poorly differentiated mixe d adenocarcinoma/small cell carcinomas in 3 cases. Tumor sites include d the rectum (six cases), appendix (four cases), small bowel (two case s), and sigmoid colon (two cases). High-grade dysplasia was present in adjacent mucosa in four cases, and low-grade dysplasia was present in distant mucosa in two cases. Two patients with poorly differentiated NENs died from the disease at 3 and 11 months after tumor excision. Al l of the other patients were alive without tumor as of last follow-up. We concluded that NENs rarely arise in a setting of IBD. Most are wel l-differentiated tumors and are clinically indolent. Dysplasia is foun d in adjacent mucosa in more than one-third of cases, suggesting that neuroendocrine differentiation might evolve from multipotential cells in dysplastic epithelium.