A risk stratification algorithm for lesions of uncertain malignant potential diagnosed by vacuum-assisted breast biopsy (VABB) of mammographic microcalcifications.

PURPOSE: To investigate a risk stratification strategy for lesions of uncertain malignant potential (B3) diagnosed by vacuum-assisted breast biopsy (VABB) of mammographic microcalcifications. METHODS: Patients who underwent VABB for microcalcification-only lesions with a diagnosis of B3 and subsequent surgery were included in this retrospective, IRB-approved study. Seventy-six B3-lesions (final histology: 66 benign, 10 malignant) were included (Tr). Data on B3 lesion type and presence of atypia, microcalcification characteristics (BI-RADS), removal at biopsy and concomitant lesions were collected. After univariate analysis (Chi-square test), data were combined into a risk stratification algorithm by using a ten-fold, cross-validated Classification and Regression Tree analysis (CRT). The algorithm was tested on a testing dataset (Te) of 23 B3-lesions (six malignant, 17 benign). RESULTS: Malignancy was more frequent in women with a concomitant cancer (P < 0.001) and highly suspicious microcalcifications (P < 0.001). The CRT algorithm retained three characteristics: morphology; presence of atypia; presence of concomitant cancer. The algorithm identified 25/76 (32.9 %,Tr) and 6/23 (26.1 %,Te) lesions at low risk of malignancy. No malignant cases were identified at surgery (0/31). There were 3/76 (3.9 %,Tr) and 1/23 (4.3 %,Te) lesions assigned as high-risk by the algorithm and confirmed at surgery (4/4). In the remaining lesions (48/76, 63.1 %,Tr; 16/23, 69.6 %,Te), malignancy rates varied between 9% and 88.4 %; thus, surgery could not have been avoided. CONCLUSION: We constructed and tested a risk stratification algorithm for B3 microcalcifications, including clinical, imaging, and pathological features, to assign probabilities of malignancy, which has the potential to reduce unnecessary surgeries.

Is breast MRI a helpful additional diagnostic test in suspicious mammographic microcalcifications?

PURPOSE: Microcalcifications are a common finding in mammography and usually require invasive procedures to diagnose or exclude malignancy. As many microcalcifications are due to benign lesions, we wanted to assess whether breast MRI as an additional diagnostic tool may be used to distinguish benign from malignant in this setting. MATERIALS AND METHODS: Eligible for this retrospective, IRB-approved observational study were 858 consecutive patients (mean age 54±11years) undergoing stereotactically-guided biopsies of suspicious mammographic microcalcifications during three year at our institution. Finally included were 152 patients who also underwent breast MRI <8weeks prior to biopsy. In case of malignant or lesions of uncertain malignant potential, subsequent surgery was performed. Benign findings were confirmed by imaging follow-up. BI-RADS category assignments from the original mammography and breast MRI reports were compared to the final diagnosis (benign vs. malignant) to determine diagnostic benchmarks. RESULTS: Histopathology revealed 81 benign (53.3%), 41 DCIS (27%) and 30 (19.7%) invasive cancers. Sensitivity, specificity, positive and negative predictive values for breast MRI were 97.2% (69/71), 39.5% (32/81), 58.5% (69/118) and 94.1% (32/34), respectively. Thus, 32/81 unnecessary biopsies in benign lesions (39.5%) may have been avoided, missing 2/71 malignant lesions (2.8%), both DCIS G2. CONCLUSION: Breast MRI as an additional diagnostic tool can be used to accurately distinguish benign from malignant mammographic microcalcifications and may thus be helpful to reduce unnecessary breast biopsies.