The diagnostic value of contrast-enhanced ultrasound combined with clinicopathological features in microinvasive ductal carcinoma

Background: Ductal carcinoma in situ with microinvasion (DCISM) represents 1% of all breast cancer cases and is arguably a more aggressive subtype of ductal carcinoma in situ (DCIS). Preoperative evaluation of DCISM usually relies on core needle biopsy, and non-invasive evaluation methods are relatively limited. This study aims to explore the features of conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) in DCISM and to analyze the US and clinicopathological predictors of infiltrating components. Methods: A retrospective collection of US, CEUS, and clinicopathologic data for DCIS and DCISM lesions was conducted from January 1, 2019 to June 30, 2022. The Breast Imaging Reporting and Data System (BI-RADS) criteria were used to evaluate breast lesions. On CEUS, the imaging features were scored using a 5-point scoring system to re-rate the BI-RADS category indicated by conventional US features. The pathological diagnosis served as the gold standard. Histopathologic features included comedo-type necrosis and pathological grade, while biomarkers included estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and the Ki-67 index. A logistic regression analysis was performed to identify the independent risk factors for DCISM. The diagnostic performance of the model was evaluated using the receiver operating characteristic (ROC) curve and calculating the area under the curve (AUC). Results: A total of 89 women were included in the study. Of these, 66 had a pathologic diagnosis of DCIS (66 lesions, ranging in size from 0.6 to 4.9 cm), and 23 had a pathologic diagnosis of DCISM (23 lesions, ranging in size from 0.7 to 4.2 cm). Three features on conventional US (tumor size, margin, and calcification) and three enhancement features on CEUS (enhancement margin, enhancement mode, and enhancement scope) were found to be significantly different between the DCIS and DCISM lesions (P=0.03, P=0.04, P=0.02, P=0.03, P=0.03, P=0.007, respectively). Patients with DCISM were more likely to have a higher pathological grade, ER negativity, PR negativity, HER2 positivity, and a higher Ki-67 index than patients with DCIS (P<0.001, P=0.042, P=0.03, P=0.009, P=0.05, respectively). A multivariate logistic regression analysis further showed that only an enlarged enhancement scope and pathological grade were associated with DCISM. The sensitivity and specificity of this predictive model were 87.0% and 81.8%, respectively (AUC =0.89). The absence of calcifications, non-mass lesions, lack of vascularity, and the non-enlarged scope can lead to misdiagnosis of DCIS and DCISM. Conclusions: Understanding the CEUS and clinicopathologic features of DCISM lesions may alert clinicians to the possibility of microinvasion and guide appropriate management.