What is the appropriate method of pathological specimen collection for cholangiocarcinoma detection in primary sclerosing cholangitis?

Background In primary sclerosing cholangitis (PSC), it is important to understand the cholangiographic findings suggestive of malignancy, but it is difficult to determine whether cholangiocarcinoma is present due to modifications caused by inflammation. This study aimed to clarify the appropriate method of pathological specimen collection during endoscopic retrograde cholangiopancreatography for surveillance of PSC. Methods A retrospective observational study was performed on 59 patients with PSC. The endpoints were diagnostic performance for benign or malignant on bile cytology and transpapillary bile duct biopsy, cholangiographic findings of biopsied bile ducts, diameters of the strictures and upstream bile ducts, and their differences. Results The sensitivity (77.8% vs. 14.3%, P = 0.04), specificity (97.8% vs. 83.0%, P = 0.04), and accuracy (94.5% vs. 74.1%, P = 0.007) were all significantly greater for bile duct biopsy than for bile cytology. All patients with cholangiocarcinoma with bile duct stricture presented with dominant stricture (DS). The diameter of the upstream bile ducts (7.1 (4.2–7.2) mm vs. 2.1 (1.2–4.1) mm, P