Diagnostic Concordance of Phyllodes Tumour of the Breast

Rakha, Emad; Mihai, Raluca; Abbas, Areeg; Bennett, Rachel; Campora, Michela; Morena, Philippa; Toss, Michael; Ellis, Ian

Abstract

Background: Phyllodes tumours (PT) are rare and distinct breast tumours, which span a morphological continuum. Classification into benign, borderline and malignant categories reflects their biology and clinical behaviour and is essential to guide management. This study aims to assess the diagnostic agreement of PT using the UK National Health Service Breast Screening Programme (NHSBSP) breast pathology external quality assurance (EQA) scheme data.

Methods: 26 PTs were identified in the EQA scheme, which were diagnosed by an average of 607 participants/circulation. Data on diagnostic categories were collected, and representative slides were reviewed. The level of concordance between reporting pathologists was assessed.

Results: There were 14 benign, 6 borderline and 6 malignant PT. The overall rate of diagnosis agreement was 86% when analysed as benign lesions, borderline PT and malignant lesions, which decreased to 79% when diagnosed as PT (irrespective of grade) and to 63% when the diagnosis was further refined to PT categories (benign, borderline and malignant PTs). The highest agreement rate was observed in malignant PT (86%) and the lowest in borderline PT (42%). Malignant heterologous elements, stromal overgrowth and leaf-like architecture are features associated with higher concordance rates. Lower priority features were stromal expansion, clefting, and multinodularity.

Conclusion: The concordance of PT diagnosis, as an entity, is high, but its classification into benign, borderline and malignant has variable agreement levels, with borderline tumours having the lowest concordance rate. More research to refine the diagnostic criteria for categorisation of PT is warranted to improve concordance between pathologists.

• Journal Article Type: Article
• Acceptance Date: May 4, 2021
• Online Publication Date: May 9, 2021
• Publication Date: 2021-10
• Deposit Date: May 12, 2021
• Publicly Available Date: May 10, 2022
• Journal: Histopathology
• Print ISSN: 0309-0167
• Electronic ISSN: 1365-2559
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 79
• Issue: 4
• Pages: 607-618
• DOI: https://doi.org/10.1111/his.14397
• Keywords: Phyllodes tumour; concordance; fibroepithelial lesions; diagnostic agreement Short Title: Phyllodes tumour diagnostic concordance 2
• Public URL: https://nottingham-repository.worktribe.com/output/5526967
• Publisher URL: https://onlinelibrary.wiley.com/doi/10.1111/his.14397