Coexistence of Crohn's disease and neuroendocrine tumour of appendix: more than coincidence?

A rare cecal subepithelial tumor in a Crohn´s Disease patient

Appendiceal tumors comprise a variety of histologic types, including appendiceal mucinous neoplasms, which can be grouped as premalignant lesions, tumors of uncertain malignant potential, and malignant lesions. The appendiceal mucinous neoplasms are characterized by mucinous epithelial proliferation with extracellular mucin and pushing tumor margins, commonly an incidental finding during operative exploration. We report the case of a low-grade appendiceal mucinous neoplasm presenting as a subepithelial lesion in Crohn´s Disease patient. The diagnosis was not straightforward, and only surgical resection allowed an accurate diagnosis. Although Inflammatory Bowel Disease is a risk factor for the development of colorectal neoplasms, the absolute risk for appendiceal tumors is uncertain. The frequency of progression to malignancy remains to be determined.

Is the prevalence of colonic neuroendocrine tumors increased in patients with inflammatory bowel disease?

Inflammatory bowel disease (IBD) patients may bear an increased neuroendocrine tumor (NET) risk. These tumors are mostly reported as coincidental findings during surgery. We aimed to determine the prevalence of colonic NET in a Dutch nationwide IBD cohort and calculate the prevalence rate ratios (PRR) compared with the general Dutch population. Our second aim was to investigate whether a high bowel surgery rate in IBD could result in a high PRR for NET. The Dutch Pathology Registry (PALGA) was searched to identify all IBD patients with colonic NET in The Netherlands between 1991 and 2011. We determined the prevalence and PRR of colonic NET in a 20-year period. For our second aim, we compared NET prevalence in colonic resection specimens between IBD cases and non-IBD controls (diverticulitis and ischemia). We identified 51 IBD patients who developed colonic NET resulting in a prevalence of 60.4-89.3 per 100,000 patients in a 20-year period with a PRR of 2.8-4.1. However, adjusted for resection type, sex and age, a higher NET prevalence was shown in diverticulitis (OR 5.52, 95% CI 3.47-8.78) and ischemia (OR 1.97, 95% CI 1.09-3.58) compared with IBD. Our key finding is that NET are more prevalent in IBD patients compared with the general population (PRR 2.8-4.1). This might be attributed to a high rate of incidental NET as IBD patients frequently undergo intestinal surgery. A lower adjusted NET prevalence in colonic resection specimens for IBD compared to ischemia and diverticulitis supports this hypothesis.