Brush cytology of the extrahepatic biliary tract: comparison of cytologic features of adenocarcinoma and benign biliary strictures.

Malignant strictures of the extrahepatic biliary tract are difficult to discern from benign strictures solely by clinical and/or radiographic findings. Endoscopic retrograde wire-guided brushings of strictures have proven to be useful in evaluating such lesions. Because the reported sensitivity of diagnosing adenocarcinoma of the extrahepatic biliary tract by this technique has varied considerably (44 to 100%), we undertook a retrospective study to determine if the diagnostic accuracy could be increased by identifying key cytologic features by reviewing a series of 90 biliary tract brushings from 80 patients. The cytologic diagnosis was confirmed either by additional pathologic material and/or clinical follow-up. Utilizing a multiple logistic regression analysis, three key cytologic features were identified that were useful in separating benign from malignant strictures; these features included: nuclear molding, chromatin clumping, and increased nuclear-cytoplasmic ratio. The presence of two of these three features resulted in a sensitivity of 83%; the corresponding specificity was 98%. The use of these key features should aid the cytologist in better recognizing malignant cells in biliary tract brushings.