Cytologic diagnosis of adenocarcinoma on bile duct brushings in the presence of stent associated changes: A retrospective analysis.

Background: Bile duct brushing (BDB) cytology, for the characterization of bile duct strictures, can be challenging to interpret when associated with a stent. Our study aims to identify the cytologic criteria for the diagnosis of adenocarcinoma in BDBs in the presence of a stent.

Methods: A database search (January 2010-December 2015) identified three groups of BDBs-negative with stent, malignant with stent, malignant without stent. All malignant cases had histologic and/or cytologic evidence of malignancy within 1 month of the brushing sample. All reactive cases had ≥6 months of benign clinical follow-up. ThinPrep slides were reviewed by two cytopathologists and cytologic features were recorded. Statistical analysis was performed using Fisher's exact test.

Results: The study cohort included 12 reactive cases with stent, 17 malignant cases with stent and 32 malignant cases without stent. Among the stented cases, the cytologic features that reached statistical significance were 3D architecture, anisonucleosis to the extent of ≥1:6, coarse chromatin distribution and the presence of single atypical cells in the malignant group in contrast to the benign group. Cases that were diagnosed malignant in the presence of a stent revealed a spectrum of cell populations more frequently as compared with the malignant cases without stent (76% vs 16%).

Conclusion: Our findings reveal that the cytologic features of malignancy in non-stented BDBs mostly hold true for stented specimens as well. Application of these criteria in the presence of a stent can improve diagnostic accuracy and thereby patient care.