Background: The sensitivity of transpapillary biliary forceps biopsy for malignancy has been reported as varying from 43-81%. Therefore, there are false negatives in more than 20% of patients, which makes it difficult to diagnose benign biliary stricture as benignancy in a clinical setting. Methods: To clarify the number of tissue samples that should be obtained during transpapillary forceps biopsy to distinguish benign biliary stricture from malignancy, patients undergoing transpapillary biliary forceps biopsy at our institute were examined retrospectively in this study. Results: Seventy-two biliary forceps biopsy procedures were performed on 61 patients. The final diagnoses were malignant biliary stricture in 34 patients and benign stricture in 27 patients. The overall sensitivity and specificity for malignancy in this study were 76.5% and 100%, respectively. There were zero out of 10 (0%) false-negative patients when three or more tissue samples were obtained. In contrast, when four or more tissue samples were obtained, eight out of eight (100%) patients had negative diagnoses for malignancy and were finally diagnosed with benignancy. Conclusion: We suggest that three or more tissue samples are recommended for the diagnosis of biliary malignant stricture.
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