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The Concordance between Cytological and Histological Specimens of Bile Duct and Malignancy Rates of Cytological Specimens: A Study in a Single Institution

Background: Cytological evaluation of biliary tract specimens, especially from the common bile duct, is a procedure to identify potential malignant lesions that is less invasive than resection. Staffs of cytological service examined cytological specimens from the bile duct. Following this, tissue biopsy or resection was conducted and the diagnostic discrepancies between the two procedures were analyzed.

Objective: To investigate the diagnostic concordance rates from the histological and the cytological examination of bile duct specimens and to evaluate the malignancy rate according to the bile duct cytological diagnostic category.

Materials and Methods: Seventy-eight cytological bile duct specimens were collected between January 2011 and September 2017. In addition, 44 histological biopsied or resected specimens were retrospectively included in the present study. The Kappa coefficient was calculated and used to determine the concordance rate between the two procedures. The sensitivity and positive predictive value of cytology were calculated and compared to histological biopsied or resected specimens. The malignancy rates among the cytological diagnostic categories were identified.

Results: There was moderate concordance between the cytology and the biopsy or resected specimens (K=0.52, p=0.001), the sensitivity and specificity of which were 75% (95% CI 47.62 to 92.73) and 79% (95% CI 59.05 to 91.70), respectively. The positive predictive value was 67 (95% CI 48.24 to 81.10), and negative predictive value was 85% (95% CI 69.73 to 92.92). The malignancy rate in the negative for malignancy group was 18%.

Conclusion: The diagnostic concordance rate between the cytological results of bile duct specimens and the results of biopsy or resection was 77% (95% CI 62 to 88), with a moderate concordance rate (K=0.52, p=0.001).

Keywords: Bile cytology, Bile duct, Cytology, Histology, Concordance rate, Bile duct cancer