Diagnostic interobserver variability of atypia assessment in columnar cell lesions among a group of expert breast pathologists in the United Kingdom and the Republic of Ireland, on behalf of the UK national coordinating committee for breast pathology

Soha El Sheikh; Mohamed A Mansour; Elena Provenzano; Abeer Shaaban; Andrew Lee; Yasmeen Mir; Rebecca McMillan-Slater; Pauline Carder; Silvana Di Palma; Clinton Boyd; Purnima Makhija; Madhuri Warren; Susan Pritchard; Rahul Deb; Ian Ellis; Emad Rakha; Cecily Quinn; Sarah Pinder

doi:10.1111/his.15402

Diagnostic interobserver variability of atypia assessment in columnar cell lesions among a group of expert breast pathologists in the United Kingdom and the Republic of Ireland, on behalf of the UK national coordinating committee for breast pathology

Histopathology. 2024 Dec 20. doi: 10.1111/his.15402. Online ahead of print.

Authors

Soha El Sheikh^{1

2}, Mohamed A Mansour², Elena Provenzano^{3

4}, Abeer Shaaban^{5

6}, Andrew Lee⁷, Yasmeen Mir⁸, Rebecca McMillan-Slater⁹, Pauline Carder¹⁰, Silvana Di Palma¹¹, Clinton Boyd¹², Purnima Makhija¹³, Madhuri Warren¹³, Susan Pritchard¹⁴, Rahul Deb¹⁵, Ian Ellis^{7

16}, Emad Rakha^{7

16}, Cecily Quinn^{17

18}, Sarah Pinder^{19

20}

Affiliations

¹ Research Department of Pathology, University College London (UCL) Cancer Institute, London, UK.
² Department of Histopathology, Royal Free London Foundation Trust, London, UK.
³ Addenbrookes Hospital and NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
⁴ Department of Histopathology, Addenbrookes Hospital, Cambridge, UK.
⁵ Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK.
⁶ Cellular Pathology, Queen Elizabeth Hospital Birmingham, Birmingham, UK.
⁷ Histopathology Department, Nottingham University Hospitals NHS Trust, City Hospital Campus, Nottingham, UK.
⁸ Pathology, Liverpool University Hospitals Foundation Trust, Liverpool, UK.
⁹ Department of Cellular Pathology, St James's University Hospital, Leeds, UK.
¹⁰ Bradford Teaching Hospitals NHS Trust, Duckworth Lane, Bradford, UK.
¹¹ Cellular Pathology Department, Royal Surrey Hospital NHS Foundation Trust, Guildford, UK.
¹² Histopathology, Belfast Health and Social Care Trust, Belfast, UK.
¹³ Pathology, Barts Health NHS Trust, London, UK.
¹⁴ Pathology, Wythenshawe Hospital Manchester Foundation Trust, Manchester, UK.
¹⁵ Cellular Pathology, University Hospitals of Derby and Burton NHS Foundation Trust, Derby, UK.
¹⁶ Academic Unit for Translational Medical Sciences, School of Medicine, University of Nottingham, Nottingham, UK.
¹⁷ Department of Histopathology, St Vincent's University Hospital, Dublin, Ireland.
¹⁸ University College Dublin School of Medicine, Dublin, Ireland.
¹⁹ School of Cancer and Pharmaceutical Sciences, Kings College London, London, UK.
²⁰ Department of Cellular Pathology, Guy's and St Thomas' NHS Foundation Trust, London, UK.

PMID: 39704183
DOI: 10.1111/his.15402

Abstract

Aims: Atypical ductal hyperplasia and flat epithelial atypia (FEA) have defined diagnostic criteria, yet there is variation in the interpretation of these criteria, particularly when the atypia is present in a background of columnar cell lesions (CCLs). This study focuses upon cases which are especially challenging or difficult to classify reproducibly according to existing criteria.

Methods and results: Thirteen breast pathology experts were asked to classify 10 challenging cases with CLLs as atypical or non-atypical. Interobserver agreement was calculated. After two consensus meetings, which explored the morphological features underlying the decision, the cases were reassessed. Finally, a photomontage was compiled as a visual aid for practising pathologists representing a range of straightforward cases and others where subjective interpretation causes disagreement within current diagnostic criteria. Overall interobserver agreement and pairwise pathologist agreement coefficients were both in the fair range (κ = 0.22 and κ = 0.3-0.4, respectively). This improved to moderate or substantial agreement (κ = 0.6-0.8) after two consensus meetings. The most controversial cases were atypical cases that lacked the regular rounded nuclei of FEA, and non-atypical cases that had florid architectural changes bordering on architectural atypia.

Conclusion: Among expert breast pathologists, interobserver agreement in the diagnosis of atypia in CCLs was higher in cases with classical features of FEA. Consensus was difficult to achieve if nuclear or architectural atypia fell outside the classical definition of FEA, suggesting that this category does not encompass the range of low-grade cytological atypia in CLLs. This study provides rationale for expanding the definition of atypia in CCLs other than FEA.

Keywords: B3 lesion; atypical intraductal epithelial proliferation; columnar cell lesions; flat epithelial atypia; interobserver variation; lesions of uncertain malignant potential.