Bile duct brushing cytology: Cytohistologic/fine-needle aspiration correlation and diagnostic pitfalls

Bile duct brushings are a mainstay in the work-up of patients who present with clinical findings of pancreaticobiliary disease. This study presents the University of Wisconsin Hospital and Clinics Cytopathology Laboratory's experience over a 10.5-year period with histologic and fine-needle aspiration (FNA) correlation.

From January 1, 2005, through June 30, 2015, 676 bile duct brushings were processed, of which 408 (60%) were negative, 84 (12%) were atypical, 65 (10%) were suspicious, and 119 (18%) were malignant. Histologic and FNA follow-up was available in 285 (42%) of the cases and forms the basis of this study.

There were 59 (21%) positive, 38 (13%) suspicious, 54 (19%) atypical, and 134 (47%) negative bile duct brushings with follow-up. Of the 59 positive cases, 57 (97%) were malignant and 2 (3%) were negative on histologic/FNA follow-up. Thirty-three (87%) of the suspicious brushing were malignant on follow-up and 5 (13%) were negative; 43 (80%) of the atypical brushings were malignant and 11 (20%) were negative; and 94 (70%) of the negative brushings were malignant and 40 (30%) were negative on histologic/FNA follow-up. The sensitivity was 38%; specificity, 95%; positive predictive value, 97%; negative predictive value, 30%.

Bile duct brushing cytology is highly specific in the detection of malignant pancreatobiliary lesions with few false positives, but has low sensitivity with many false negatives.