Breast ultrasonographic and histopathological characteristics without any mammographic abnormalities.

OBJECTIVE We evaluated ultrasonographic findings and the corresponding histopathological characteristics of breast cancer patients with Breast Imaging Reporting and Data System (BI-RADS) category 1 mammogram. METHODS We retrospectively reviewed the ultrasonographic findings and the corresponding histopathological features of 45 breast cancer patients with BI-RADS category 1 mammogram and 537 controls with mammographic abnormalities. We evaluated the ultrasonographic findings including mass shape, periphery, internal and posterior echo pattern, interruption of mammary borders and the distribution of low-echoic lesions, and the corresponding histopathological characteristics including histological classification, hormone receptor and human epidermal growth factor receptor 2 status of invasive ductal carcinoma and ductal carcinoma in situ, histological grade, mitotic counts and lymphovascular invasion in individual cases of BI-RADS category 1 mammograms and compared with those of the control group. RESULTS The ultrasonographic characteristics of the BI-RADS category 1 group were characterized by a higher ratio of round shape (P< 0.001), non-spiculated periphery (P= 0.021), non-interruption of mammary borders (P< 0.001) and non-attenuation (P= 0.011) compared with the control group. A total of 52.6% of low-echoic lesions were associated with spotted distribution in the BI-RADS 1 group, whereas 25.8% of low-echoic lesions were associated with spotted distribution in the control group (P= 0.012). As for histopathological characteristics, there was a statistically higher ratio of triple-negative subtype (P= 0.021), and this particular tendency was detected in histological grade 3 in the BI-RADS category 1 group (P= 0.094). CONCLUSION We evaluated ultrasonographic findings and the corresponding histopathological characteristics for BI-RADS category 1 mammograms and noted significant differences among these findings in this study. Evaluation of these ultrasonographic and histopathological characteristics may provide a more accurate ultrasonographic screening system for breast cancer in Japanese women.