[Objective] The objective of this study was to evaluate the diagnostic accuracy of the 2013 edition of Breast Imaging Reporting and Data System (BI-RADS) ultrasound lexicon in diagnosing breast categories 3-5 lesions.[Methods] Using our breast ultrasound database from June 2014 to June 2016,we identified 4428 BI-RADS category 3 to 5 lesions with a known pathological diagnosis in 4 428 adult women.The positive predictive value (PPV) of each BI-RADS category was calculated based on the pathological diagnoses and compared with the reference range provided by the American College of Radiology (ACR).[Results] 4 428 lesions from 4428 patients were included in this study.The PPV of each BI-RADS category waswithin the reference range provided by the ACR in 2013.1198 (27.1％) pathological malignant/borderline results were found in the 4 428 lesions,the other 3 230 (72.9％)lesions were diagnosed with benign results.Among the malignant/borderline lesions,the rate of lymph node metastasis gradually increased as the BI-RADS categories were upgraded.Malignant lesions with a diagnosis ofinvasive ductal carcinoma or invasive lobular carcinoma showed an increasing distribution trend from category 3 to 5.[Conclusion] The 2013 editionof BI-RADS ultrasound lexiconhas good diagnostic accuracy and efficiencyin clinical practice.

ObjectiveTo investigate the difference of ultrasound characteristics between pure mucinous carcinoma （PMC） and fibroadenoma （FA） of the breast. MethodsUltrasound data of 50 continuous patients with breast PMC from January 2012 to January 2021 and 100 continuous patients with breast FA from June 2018 to January 2019 in Sun Yat-sen Memorial Hospital of Sun Yat-sen University were retrospectively reviewed. The ultrasound characteristics of the two groups were evaluated according to the 2013 BI-RADS Ultrasound Atlas， and the differences in age， maximum diameter and ultrasound characteristics between the two groups were compared. ResultsThe median age of PMC patients was 47 years and that of FA patients was 33 years. The age of PMC patients was higher than that of the FA group， and the difference between the two groups of patients was statistically significant （P<0.001）. The median maximum diameter of PMC patients was 2.4 cm， which was greater than that of the FA group （1.8 cm）， and the difference was statistically significant （P=0.001）. Of the PMC， 70% （35/50） were irregular， 82% （41/50） were parallel to the skin， 92% （46/50） had no circumscribed margin， 72% （36/50） were hypoechoic， and 68% （34/50） had enhanced posterior echo. Of the FA， 69% （69/100） were oval or round， 98% （98/100） were parallel to the skin， 54% （54/100） had circumscribed margin， 98% （98/100） were hypoechoic， and 75% （75/100） had no posterior features. The differences in the above ultrasound characteristics between the PMC and FA groups were statistically significant （P<0.001， P=0.001， P<0.001， P<0.001， P<0.001）. There was no significant difference between calcifications and blood flow. ConclusionsCompared with the FA group， patients with PMC are older and the diameter of the lesions are larger. On ultrasound， the morphology and margin of most breast PMC still show the growth characteristics of invasive cancer. Meanwhile， the posterior echo of PMC is enhanced， which is a unique manifestation.