Dysplastic crypts in asymmetric branching found in ulcerative colitis-associated dysplasia

Background: Biopsies from patients with ulcerative colitis (UC) often show crypt branching´s (CB).

Aims: The purpose was to analyze the frequency of CB in biopsies with dysplasia in UC (D-UC).

Methods: Digitalized-sections from 49 consecutive D-UC cases were reviewed and all CB were recorded. Potential confounders such as gender, age, UC-duration, localization in the colorectum, degree of epithelial dysplasia and number of mucosal samples/biopsy, were investigated.

Results: A total of 334 dysplastic CB (DCB) were recorded in the 49 D-UC cases; 321 (96.1%) DCB were in asymmetric branching (DCAB), and the remaining 13 (3.9%), in symmetric branching (DCSB). Out of the 49 D-UC cases, 41% had 1-4 DCAB, 43% 5-9 DCAB, 10% 10-15 DCAB, and the remaining 6%, ≥ 16 DCAB. Low-grade dysplasia (LGD) was present in 44 (90%) of the 49 D-UC cases, and high-grade dysplasia (HGD) in the remaining 5 (10%). The frequency of DCAB was not influenced by age, gender, biopsy site (right colon, left colon, or rectum), number of mucosal samples/biopsy, degree of dysplasia or UC duration.

Conclusions: Two novel histologic phenotypes of DCB in UC-associated dysplasia are reported, namely DCAB and DCSB. The wide variation in DCAB-frequency in UC-associated dysplasia suggests potential biological differences between cases.