Interobserver agreement and risk of malignancy using the International Academy of Cytology Yokohama System for reporting breast FNA biopsy in a liquid‐based exclusive cohort

• Published in: Cancer cytopathology 2024-05, Vol.132 (5), p.320-326
• Main Authors: Folarin, Olawunmi, Kim, David, Gokozan, Hamza N., Heymann, Jonas J., Scarpa Carniello, Jose V., Rosado, Lucelina, Siddiqui, Momin T., Patel, Ami
• Format: Article
• Language: English
• Subjects: Adult; Aged; Biopsy; Biopsy, Fine-Needle - methods; breast; Breast Neoplasms - diagnosis; Breast Neoplasms - pathology; Cellular biology; Cohort Studies; Cytodiagnosis - methods; cytology; Female; fine needle aspirate; Humans; Liquid Biopsy - methods; liquid‐based cytology; Middle Aged; Observer Variation; Reproducibility of Results; Retrospective Studies
• ISSN: 1934-662X; 1934-6638; 1934-6638
• DOI: 10.1002/cncy.22798

Background Per the College of American Pathologist’s National Breast Fine Needle Aspiration Biopsy (FNAB) Practice Survey, ∼40% of laboratories use liquid‐based cytology (LBC) for breast FNAB. The reproducibility of the International Academy of Cytology Yokohama System (YS) for reporting breast FNAB on LBC was explored. Design Breast FNAB specimens submitted as LBC only (all ThinPrep) between January 2017 and January 2021 were retrieved. Cases without histopathologic follow‐up were excluded. Clinical and radiologic information was collected. One cytologist and six cytopathologists rendered diagnoses per YS. All reviewers were blinded to the original diagnosis and histopathologic follow‐up. The risk of malignancy was calculated. Concordance rates were calculated by a weighted Cohen Kappa score (κ). Results Review of 110 cases demonstrated substantial to near‐perfect agreement between each reviewer (κ = 0.73–0.91) and follow‐up histopathology (κ = 0.66–0.85). The agreement was lowest in the inadequate (κ = 0.05) and atypical (κ = 0.04) categories. The lack of concordance in the atypical category was common in cases with low cellularity or incomplete structural features. The risk of malignancy for inadequate, benign, atypical, suspicious for malignancy, and malignant categories were 12.5% (2/16), 3% (2/65), 67%, (8/12) 100% (1/1), and 100% (16/16). Conclusion Interobserver agreement is excellent using the five YS categories in LBC. Lack of cellularity and incomplete architectural features were barriers to perfect agreement. Established pitfalls in the interpretation of LBC were cause for atypical diagnoses. Continuous training and education are recommended to avoid misdiagnosis because of the nonconventional cytomorphologic features of LBC and to improve inadequate and atypical rates within YS. Interobserver agreement is excellent using the 5 International Academy of Cytology Yokohama System (YS) categories in liquid‐based cytology (LBC). Continuous training and education are recommended to avoid misdiagnosis due to the non‐conventional cytomorphologic features of LBC and to improve inadequate and atypical rates within YS.