Impact of Non-Calcified Specimen Pathology on the Underestimation of Malignancy for the Incomplete Retrieval of Suspicious Calcifications Diagnosed as Flat Epithelial Atypia or Atypical Ductal Hyperplasia by Stereotactic Vacuum-Assisted Breast Biopsy

OBJECTIVE: Stereotactic vacuum-assisted breast biopsy (VABB) is considered a reliable alternative to surgical biopsy for suspicious calcifications. In most cases, the management of flat epithelial atypia (FEA) and atypical ductal hyperplasia (ADH) after VABB with residual calcifications requires surgical excision. This study aimed to evaluate the impact of pathology of non-calcified specimens on the underestimation of malignancy. MATERIALS AND METHODS: We retrospectively reviewed 1147 consecutive cases of stereotactic VABB of suspicious calcifications without mass from January 2010 to December 2016 and identified 46 (4.0%) FEA and 52 (4.5%) ADH cases that were surgically excised for the retrieval of residual calcifications. Mammographic features and pathology of the calcified and non-calcified specimens were reviewed. RESULTS: Seventeen specimens (17.3%) were upgraded to malignancy. Mammographic features associated with the underestimation of malignancy were calcification extent (> 34.5 mm: odds ratio = 6.059, p = 0.026). According to the pathology of calcified versus non-calcified specimens, four risk groups were identified: Group A (ADH vs. high-risk lesions), Group B (ADH vs. non-high-risk lesions), Group C (FEA vs. high-risk lesions), and Group D (FEA vs. non-high-risk lesions). The lowest underestimation rate was observed in Group D (Group A vs. Group B vs. Group C vs. Group D: 35.0% vs. 20.0% vs. 15.0% vs. 3.6%, p = 0.041, respectively). CONCLUSION: Considering that the calcification extent and pathology of non-calcified specimens may be beneficial in determining the likelihood of malignancy underestimation, excision after FEA or ADH diagnosis by VABB is required, except for the diagnoses of FEA coexisting without atypia lesions in non-calcified specimens.