Background  Microinvasion is the intermediate stage in the transition of breast intraductal carcinoma into invasive intraductal carcinoma, and the diagnosis and treatment of such patients before and during the stage is of great significance to improve the prognosis of patients, but at present, there is still a lack of large-sample studies on the influencing factors for breast intraductal carcinoma with microinvasion.

  Objective  To investigate the pathological and ultrasound features of breast intraductal carcinoma with microinvasion and the influencing factors for diagnosis.

  Methods  A retrospective analysis was performed for the clinical data about 149 patients with breast intraductal carcinoma who were admitted to Xiyuan Hospital from July 2018 to July 2021, and according to the presence or absence of microinvasion, the patients were divided into microinvasion group (n=87) and non-microinvasion group (n=62). Their pathological and ultrasound features were analyzed. Multivariate logistic regression analysis was used to identify the influencing factors for breast intraductal carcinoma with microinvasion, and receiver operating characteristic (ROC) curve analysis was used to investigate the value of several indicators in the diagnosis of breast intraductal carcinoma with microinvasion.

  Results  Univariate analysis showed that there were significant differences between the microinvasion group and the non-microinvasion group in the proportion of patients with palpable mass or menopause, histological grade, the presence of estrogen receptor (ER) and progesterone receptor (PR), the expression of human epidermal growth factor receptor 2 (HER-2) and Ki67, morphology, tumor boundary, echo, ductal changes, blood flow grade, and marked calcification (all P<0.05). Multivariate logistic regression analysis showed that high/intermediate histological grade, negative ER, negative PR, high HER-2 expression, high Ki67 expression, unclear tumor boundary, low echo, grade 2/3 blood flow, and marked calcification were independent risk factors for breast intraductal carcinoma with microinvasion (all P<0.05). ROC curve analysis showed that ER, PR, HER-2, and Ki67 showed good values in the diagnosis of breast intraductal carcinoma with microinvasion, with an area under the ROC curve of 87.3% (95% CI, 79.1%-93.1%), a sensitivity of 0.862 (75/87), a specificity of 0.839 (52/62), and an accuracy of 0.852 (127/149).

  Conclusion  The development of breast intraductal carcinoma with microinvasion is associated with the histological grade of patients, tumor edge, echo, blood flow grade, calcification and the expression of ER, PR, HER-2, Ki67.