Reproducibility of the "International Academy of Cytology Yokohama System for Reporting Breast Cytology" - A Retrospective Analysis of 70 Cases.

Background: Fine-needle aspiration cytology (FNAC) is the most practiced initial method for evaluation of breast lesions. The International Academy of Cytology Yokohama System for Reporting Breast (IAC YSRB) Fine-Needle Aspiration Biopsy Cytopathology has been developed to standardize the reporting system. However, literature available on the inter-observer reproducibility of 5 IAC YSRB categories is limited.

Aim: We investigated the inter-observer reproducibility of the IAC YSRB system.

Method And Materials: A total of 70 consecutive specimens obtained from FNAC of breast lesions were reviewed retrospectively by 3 experienced cytopathologists who allotted 1 to 5 IAC YSRB categories.

Results: The percent overall agreement between observers was 70.48% and the free marginal kappa was 0.63, which signifies substantial agreement. After combining "Suspicious" and "Malignant" categories, overall agreement was 80.95% and free marginal kappa became 0.75.

Conclusions: Inter-observer agreement of three (70.48%) cytopathologists was substantial. Agreement can be improved by combining certain categories, especially "Suspicious" and "Malignant". Technical quality limitation plays a significant role in a proportion of cases, mainly the "Atypical" and "Suspicious of malignancy" categories. Application of the IAC YSRB system in day-to-day practice will increase the inter-observer agreement.