Microcarcinoids associated with diversion colitis in a patient with Crohn's disease

Diversion colitis is an iatrogenic disorder related to surgical diversion of the faecal stream from the colorectal mucosa, first described by Morson in 1972. Inflammation of the defunctioned mucosa seems to be related to deprivation of luminal nutrients, in particular short chain fatty acids. Histologic abnormalities include damage of the epithelium and reparative changes with crypt distortion and branching, a mixed acute and chronic inflammatory infiltrate with crypt abscesses and lymphoid hyperplasia, Paneth cell metaplasia and thickening of the muscularis mucosae. We report a case of diversion colitis in a 51-year-old female with Crohn's disease with multiple submucosal microcarcinoids in the rectal stump 17 years after diversion and discuss the hypothesis that hyperplastic and neoplastic lesions of neuroendocrine cells can result from proliferative response to chronic inflammation and repair, as well as epithelial neoplasms.