Asymmetric crypt fission in colectomy specimens in patients with ulcerative colitis.

AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.