Asymmetric crypt fission in colectomy specimens in patients with ulcerative colitis

We previously found colonic crypts with asymmetric fission bordering regenerating ulcers in ulcerative colitis (UC). The present objective was to assess the frequency of asymmetric crypt-fission in colectomy specimens from patients with long-lasting UC.

H&E-stained sections from seven colectomies from patients with UC without dysplasia or carcinoma were investigated. Symmetric fission was characterised by branched colon crypts showing ≥2 identical crypts, whereas asymmetric fission exhibited branched colon crypt portraying ≥2 dissimilar crypts, differing in diameter, length and/or shape.

The number of crypts in fission in the 89 sections was 3586; of those, 2930 (81.7%) were asymmetric and the remaining 656 (18.3%), symmetric. Out of 927 vertically-cut crypts (in well-oriented sections), 912 (98.4%) were asymmetric, and the remaining 14 (1.6%), symmetric, and out 2660, cross-cut (transected) crypts in fission, 2018 (75.9%) were asymmetric and the remaining 642 (24.1%), symmetric.

Crypt fission is rarely found in the normal colon in adults. Symmetric crypt fission found in UC is possibly triggered by a compensatory homeostatic mechanism of crypt production in mucosal areas replaced by chronic inflammation. But asymmetric crypt fission is a pathological aberration that affects crypts in patients with a particular predisposition to develop mucosal dysplasia. It is suggested that this previously unattended histological parameter be included in the pathological descriptions of colectomy specimens from patients with UC.