Abstract: Objective:?To study the clinicopathological features, immunophenotype，differential diagnosis and molecular features of mammary analogue secretory carcinoma (MASC). Methods:?Microscope observation, immunophenotyping analysis and EVT6-NTRK3 genetic testing were performed on 4 cases of MASC which were diagnosed by the Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and the Department of Pathology, Huai'an First People's Hospital from July to December 2018, and related literature was also reviewed. Results:?The patients were aged from 33 to 66 years old. The ratio of male to female was 1:1. Grossly, all cases revealed a solitary mass(1.3-2.2 cm in diameter). Microscopically, all cases demonstrated a highly infiltrative growth pattern. All tumors showed mixed growth patterns including microcystic, cystic-papillary, tubular, and solid, and eosinophilic secretions could be seen in the cavities. The mitoses were not easily found, and no coagulative necrosis, nerve or vascular invasion were found in these 4 cases. Immunohistochemically, all cases were positive for CK7, S-100, 乳腺球蛋白, SOX-10、GATA3. But DOG-1 and the other myoepithelial markers P63、α-SMA、Calponin were negative in all 4 cases. The Ki-67 proliferation index of 3 cases was less than 20%, and the other one case was about 35%. ETV6-NTRK3 gene rearrangement was detected in 3 cases by fluorescence in situ hybridization. Conclusions:?MASC is a rare low-grade salivary gland carcinoma exhibiting moderate morphology and diverse arrangement patterns. Its distinct histochemical feature - strong S-100, 乳腺球蛋白 positivity and DOG-1 negativity, can help to differentiate it from other low-grade saliva gland tumors. ETV6-NTRK3 gene rearrangement tests can be used as an auxiliary diagnostic tool if necessary.