Routine brush cytology and fluorescence in situ hybridization for assessment of pancreatobiliary strictures

Abstract

Background: The specificity of brush cytology for detection of malignant pancreatobiliary strictures is high, but its sensitivity is moderate. Fluorescence in situ hybridization (FISH) can be used to detect chromosomal aneuploidy in biliary brushing specimens, and, according to some reports, it may improve the sensitivity of routine cytology.

Objective: To assess the role of routine cytology and FISH in detection of malignant pancreatobiliary strictures.

Design: Prospective study performed between September 2008 and August 2010.

Setting: University hospital.

Patients: This study involved 81 patients with bile duct or pancreatic duct strictures.

Intervention: Brush cytology obtained during ERCP from pancreatic duct or bile duct strictures and analysis of smears by routine cytology and FISH.

Main outcome measurements: Sensitivity, specificity, and positive and negative predictive values of routine cytology and FISH calculated with a 95% confidence interval.

Results: The sensitivity of routine cytology was 35.19%, and specificity was 100%. When atypia was identified as positive, the resultant sensitivity was 53.7%, and specificity was 100%. Sensitivity of FISH was 51.85%, and specificity was 88.89%. When either routine cytology was positive or atypia was observed or when the FISH result was positive, sensitivity was the highest (72.22%), and it was statistically significant in comparison with both routine cytology with atypia (P < .036) and FISH (P < .023), but specificity was lower than that of routine cytology (88.89% vs 100%).

Limitations: Use of a DNA probe set that was designed for detection of urothelial carcinoma. Limited number of patients.

Conclusion: FISH improved the sensitivity of routine cytology. Pancreatic duct brushings were a reliable material for detection of chromosomal abnormalities by FISH. The best diagnostic result was achieved by combining routine cytology with FISH.