Abstract: Background and purpose: Breast invasive ductal carcinoma (IDC) is the most common breast carcinoma, and the ultrasonographic features of its molecular subtypes has great clinical value. The purpose of this study was to discuss the correlation between ultrasonographic features of IDC and its molecular subtypes. Methods: Ultrasonographic features of 112 patients with preoperative integrated ultrasonographic information and pathologically confirmed IDC from Sep. 2012 to Feb. 2015 were retrospectively analyzed. Based on the immunohistochemistry results of ER (estrogen receptor), PR (progesterone receptor), HER-2 (human epidermal growth factor receptor-2) and Ki-67, these cases were categorized into 4 molecular subtypes: Luminal A group, Luminal B group, ERBB2 positive group and Basal-like group. Results: There were 14 cases (12.5%) in Luminal A group, 62 cases (55.4%) in Luminal B group, 21 cases (18.7%) in ERBB2 positive group and 15 cases (13.4%) in Basal-like group. The 4 molecular subtypes differed in tumor length, lymph node involvement, tumor boundary, tumor shape and internal blood flow on ultrasonography (P<0.05). There were no significant differences in tumor internal echo, posterior echo, micro-calcification and elastrography between subtypes (P>0.05). Luminal A group and Luminal B group had less lymph node involvement, more obscure boundary and irregular shape. More internal blood flow, bigger tumor size and lymph node involvement were observed in ERBB2 positive group of this study. Patients in Basal-like group were more likely to have clear tumor boundary, regular tumor shape, bigger tumor size and lymph node involvement on ultrasonogram. Conclusion: Correlation exists between ultrasonographic features and molecular subtypes of IDC. This has tremendous clinical significance in the early diagnosis of IDC, preoperative, intraoperative and prognosis evaluation of IDC patients.

Key words: Breast invasive ductal carcinoma, Ultrasonographic features, Molecular subtypes