Purpose: Assess the upgrade rate of biopsy-proven stromal fibrosis without associated atypia
to inform the most appropriate management approach in patients with biopsy-proven stromal fibrosis without associated atypia.
Materials and Methods: REB-approved consecutive retrospective review of patient’s data of imaging-guided biopsy-proven stromal fibrosis carried out between 2014 and 2019. The upgrade rate of malignancy and the imaging features of the upgraded cases on surgical excision were recorded. The results were correlated with surgical histopathology as the ground truth or an uneventful clinical and radiological follow-up of at least 2 years. Predictors for malignancy were examined, and appropriate statistical tests were applied.
Results: Out of 9814 consecutive imaging-guided breast biopsies performed during the study period, 334 patients (4.8%) median age 52 years, had biopsy-proven stromal fibrosis without atypia and fulfilled the inclusion criteria, representing the study cohort. Out of 334 cases, 4 cases (1.2%) were upgraded to malignancy in the two years follow-up. Older patients (> 50 years) are associated with an upgrade to malignancy (p <0.001), and those with a personal history of breast cancer have a trend to upgrade to malignancy (p=0.066). No other clinical and imaging features are related to the malignancy upgrade.
Conclusion: For benign radiology-pathology concordant stromal fibrosis on imaging-guided breast biopsy, the upgrade for biopsy results demonstrating stromal fibrosis without atypia is low at 1.2% but not 0; therefore diagnostic follow-up for 2 years as BI-RADS 3 (defined as <2% chance of malignancy) is warranted. Older patient age (> 50 years) and those with a personal history of breast cancer are subgroups of patients that may justify multidisciplinary discussion and possible re-sampling.