Rates and Outcomes of Breast Lesions of Uncertain Malignant Potential (B3) benchmarked against the National Breast Screening Pathology Audit; Improving Performance in a High Volume Unit

摘要

Overdiagnosis of breast lesions of uncertain malignant potential (B3) is multifactorial and has a negative impact on patients. Subjectivity in the diagnosis of ductal atypia was identified as a potential cause for pathology overdiagnosis. Audit and team slide review were able to re-align our diagnostic rates closer to the national average and improve reporting standards, with some cases remaining a source of disagreement. Introduction: Our breast screening unit was identified as high outlier for B3 lesions with a low positive predictive value (PPV) compared to the England average. This prompted a detailed internal audit and review of B3 lesions and their outcomes to identify causes and address any variation in practice. Patients and Methods: The B3 rate was calculated in 4168 breast core biopsies from 2019, using the subsequent excision to determine the PPV. Atypical intraductal epithelial proliferation (AIDEP) cases were subject to microscopic review to reassess the presence of atypia against published cr iter ia. The B3 rate was re-audited in 2021, and the results compared. Results: Screening cases had a high B3 rate of 12.4% (30% above the national average), and a PPV of 7.7% (9.7% with atypia). AIDEP was identified as a possible cause of this outlier status. On review and by consensus, AIDEP was confirmed in only 66% of cases reported as such, 17% were downgraded, and 16% did not reach consensus, the latter highlighting the difficulty and subjectivity in diagnosis of these lesions. Repeat audit of B3 rates after this extended review revealed a reduction from 12.4% to 9.11%, which is more in line with national standards. Conclusion: Benchmarking against national reporting standards is critical for service improvement. Through a supportive environment, team working, rigorous internal review and adherence to guidelines, interobserver variation and outlier status in breast pathology screening outliers can both be addressed. This study can serve as a model to other outlier units to identify and tackle underlying causes.