Granulomatous vasculitis in diversion procto‐colitis

Diversion proctocolitis and the problem of the forgotten rectum in inflammatory bowel diseases: A systematic review

Background and aims

Diversion proctocolitis (DP) is a non‐specific mucosal inflammation arising in the defunctionalized colon and/or rectum following faecal diversion (colostomy, ileostomy). Differential diagnosis of DP from the underlying disease in patients with inflammatory bowel diseases (IBD) is often unclear. As a result, it might be difficult to undertake any specific treatment. We aimed to systematically review the literature evidence on DP in IBD patients.

Methods

For this qualitative systematic review, we searched PubMed, EMBASE and Scopus to identify all studies published until July 2021 including IBD patients affected by DP.

Results

Overall, 37 papers published between 1982 and 2021 were included. A total of 1.211 IBD patients were included: 613 UC (50.6%), 524 CD (43.3%), 66 IBD‐unclassified (IBD‐U) (5.4%), 8 unspecified patients (0.7%). Most patients with DP are asymptomatic, although inflammation is detectable in almost all patients with a rectal stump. Reduced short‐chain fatty acids and an altered microbiome, may trigger mucosal inflammation and have been proposed as causing factors. An increased risk of developing cancer on DP has been reported in patients with a history of previous dysplasia/cancer.

Conclusions

The etiopathogenesis of DP is still unknown. The efficacy of mesalamine, corticosteroids or short‐chain fatty acids has not been proven by randomized trials yet. Since the incidence of cancer of the rectal stump can reach 4.5 per 1.000 diverted patients‐year, IBD patients undergoing subtotal colectomy with end‐ileostomy should undergo close endoscopic surveillance, being eventually counseled for surgery with or without the restoration of the intestinal continuity.

An incidental enterocolic lymphocytic phlebitis pattern is seen commonly in the rectal stump of patients with diversion colitis superimposed on inflammatory bowel disease

Aims:

Enterocolic lymphocytic phlebitis (ELP) is an uncommon cause of bowel pathology and most frequently results in ischaemia. It is characterised by an artery-sparing, venulocentric lymphoid infiltrate that causes a phlebitis and vascular compromise. Rare cases of ELP have been encountered with lymphocytic colitis in the absence of ischaemic bowel change. The present study examined the occurrence of ELP in the setting of diversion colitis and inflammatory bowel disease, as well as in random colectomy specimens.

Methods:

The study cohort comprised the following: 26 completion proctectomy specimens for ulcerative colitis with superimposed diversion colitis in the rectal stump; 3 colectomy specimens for Crohn disease with diversion colitis; 6 colectomy specimens for adenocarcinoma and/or diverticular disease with diversion colitis; 34 resection specimens with ulcerative colitis only; 19 with Crohn disease only; and 100 random colon resection specimens for adenocarcinoma, adenoma, diverticular disease and ischaemia.

Results:

ELP was present in 18 of the 26 ulcerative colitis cases with diversion colitis, 3/3 Crohn disease cases with diversion colitis, 1/6 cases of diverticular disease with diversion colitis, 6/34 cases of ulcerative colitis without diversion, 2/19 Crohn disease cases without diversion colitis, and only 1 of 100 colectomy cases without inflammatory bowel disease or diversion colitis.

Conclusion:

ELP occurs most frequently in cases that have been diverted for inflammatory bowel disease. Fewer cases of ELP were noted in cases of inflammatory bowel disease in the absence of diversion colitis. It is postulated that altered bowel flora and immune dysregulation may be pivotal in the causation of this association.

Classic pathology of ulcerative and Crohn's colitis

The distinction between ulcerative colitis and Crohn's colitis has become crucially important since the introduction of pouch surgery. The classic pathologic findings in ulcerative colitis and Crohn's colitis are described, as well as the subtleties causing the difficulty in differentiation. In difficult cases, it is essential to review the whole patient, all available biopsy material, and the colectomy specimen. The diverted rectum in ulcerative colitis usually becomes more inflamed, whereas in Crohn's disease inflammation usually resolves. Upper gastrointestinal tract biopsies with apparent normal mucosa may also be contributory.