Impact of Updated 2024 Diagnostic Criteria on Early Detection of Small-Duct PSC in Ulcerative Colitis Patients: A Clinical Mini-Review Focusing on Japanese Studies

The 2024 Japanese diagnostic criteria for primary sclerosing cholangitis (PSC) introduce a paradigm shift in recognizing small-duct PSC (sdPSC), particularly within ulcerative colitis (UC) cohorts. By integrating high-resolution magnetic resonance cholangiopancreatography (MRCP) and mandatory histopathology for normal cholangiograms, these updates address prior underdiagnosis and variability in sdPSC detection. Japanese cohort studies reveal sdPSC prevalence between 5–15%, with up to 55% progressing to large-duct disease. Earlier detection, facilitated by the 2024 criteria’s 86% MRCP sensitivity and clarified histologic thresholds, may halve diagnostic delays, curbing cirrhosis and malignancy risks. In UC patients, these refinements enhance colorectal neoplasia surveillance and enable preemptive management through unified gut–liver assessment. Yet, challenges persist, including biopsy hesitancy, donor shortages, and evolving genetic insights. Overall, the updated criteria mark a decisive move toward precision hepatology, aligning Japan’s PSC-UC strategy with proactive, spectrum-based detection and management for improved long-term outcomes.