PREDICTORS OF POSITIVE BILIARY BRUSH CYTOLOGY IN PATIENTS WITH BILIARY STRICTURE

Aims Bile duct brush cytology during Endoscopic Retrograde Cholangiopancreatography (ERCP) is the standard method of sampling a biliary stricture. We aimed to find out predictors of positive brush cytology during the ERCP in patients with biliary stricture.

Methods Data were collected by retrospectively reviewing the medical records of 65 consecutive patients with indeterminate biliary stricture on imaging who underwent brush cytology at our institution from March 2017 to May 2019. We analyzed the relationship of age, sex, final diagnosis, stricture length and location, maximum diameter of the upstream dilated bile duct, serum total bilirubin, carcinoembryonic antigen, and carbohydrate antigen 19-9 with the yield of positive brush cytology.

Results The final diagnosis was benign stricture in 2 cases and malignancy in 63 cases (42 bile duct cancer, 18 pancreatic cancer, and 3 gallbladder cancer). The cytopathological diagnoses obtained were 14 negative for malignancy (21.5%), 14 atypical cells (21.5%), 11 suspicious of malignancy (16.9%), 26 malignancy (40.0%). There were no factors associated with the four cytopathological results. When patients with atypical cells were included in the positive cytology according to the final diagnosis, type of malignancy and grade of cellular differentiation were significant indicators of positive diagnosis by brush cytology (p = 0.004 and 0.038, respectively). The maximum diameter of the upstream bile duct from the stenosis tented be toward longer in the positive cytology when the location of stricture was extrahepatic bile duct (p = 0.057). The sensitivity, specificity, and accuracy of brush cytology for malignant biliary strictures were 81.0%, 100%, and 81.5%, respectively.

Conclusions Our results showed good diagnostic yields of brush cytology during ERCP for biliary stricture when atypical cells included as malignant results. Predictors of positive yield include type of malignancy and grade of cellular differentiation. Upstream bile duct dilatation tended to have a higher probability of the positive cytology.