Benign, dysplastic, or malignant--making sense of endoscopic bile duct brush cytology: results in 149 consecutive patients.

OBJECTIVES

To determine the efficacy of endoscopic bile duct brush cytology for diagnosis of pancreaticobiliary malignancies and to provide guidelines for interpretation of dysplastic cytology.

METHODS

Consecutive endoscopic bile duct brush cytology specimens were classified by an independent cytopathologist as benign, low- or high-grade dysplasia, or cancer. A final diagnosis was established in a blinded fashion by histopathology, radiographic evidence of metastatic disease, or independent clinical follow-up. Sensitivity and specificity were adjusted for dysplastic cytology, and likelihood ratios were determined for each diagnosis and used for calculation of posttest probability of malignancy.

RESULTS

Dysplasia was found in 23% of 168 consecutive bile duct brushings performed in 149 patients. Sensitivity of brush cytology was 37% and specificity 100%; its likelihood ratio for malignancy ranged from 3.4 for high-grade dysplasia, to 1.1 for low-grade dysplasia, to 0.6 for benign. For a patient with a 50% pretest probability of malignancy, finding of high-grade dysplasia changed the posttest probability to 77%, low-grade dysplasia to 52%, and benign to 38%.

CONCLUSION

Cytological dysplasia occurs frequently, with high-grade dysplasia being strongly suggestive of malignancy. Presented likelihood ratios can be used to calculate the posttest probability of malignancy for any diagnosis.