Crohn’s disease (CD) occasionally presents with continuous colonic involvement and endoscopic features resembling ulcerative colitis (UC). This UC‑like colonic CD subtype has been reported in a minority of Crohn’s colitis cases, yet understanding its endoscopic patterns and clinical characteristics is essential to improve early recognition and guide appropriate therapy.

We conducted a retrospective study including inflammatory bowel disease (IBD) patients followed in our center between 2011 and 2023.

Among 106 IBD patients (19 UC and 87 CD), UC-like CD was identified in 27 patients, accounting for 39% of colonic CD. There was a slight male predominance (M/F ratio= 1.25). The mean age at disease onset was 28.9 years, not significantly different from UC (27.9 years) or other CD (25.5 years).

Endoscopically, all UC-like CD patients showed continuous mucosal inflammation without skip lesions. Granularity, friability, and/or spontaneous bleeding were observed in 78% of cases. Pancolitis was present in 22 patients (81.5%), while 5 (18.5%) had left-sided colitis; the right colon was spared in 37%.

Histopathology favored UC in 44.4% of colonic biopsies, while 55.6% were equivocal. Ten patients underwent colectomy: histologic examination of specimens demonstrated UC features in 6 and CD features in 4 cases.

All 27 cases were ultimately diagnosed as CD rather than UC after a median delay of 53 months (IQR 3–111). Supporting arguments included the development of perianal disease (70%), ileal involvement (30%), and subsequent changes in endoscopic (52%) and histological (37%) features consistent with CD.

Active smoking was less frequent in UC-like CD than in other CD patients (3.8% vs 25%, p= 0.016). However, UC-like CD patients were more prone to develop acute severe colitis (ASC) than other colonic CD patients (55.6% vs 19%, p= 0.002). The rate of ASC was comparable between UC-like CD and UC (57.9%, p= 0.875). There was no significant difference in treatment response or surgery rates between ASC associated with UC-like CD and other ASC cases.

UC-like colonic Crohn’s disease represents a distinct subtype that closely mimics ulcerative colitis both endoscopically and histologically. Recognition of this subtype is essential, as it may evolve toward typical Crohn’s disease features over time and shows a similar risk of acute severe colitis to UC.