Objective:To discuss the effect of shear wave elastography (SWE) on the differential diagnosis of benign and malignant breast non-mass lesion (NML), and to clarify its clinical significance. Methods:A total of 158 patients with breast NML were selected and divided into benign lesion group (n=83) and malignant lesion group(n=75) according to the postoperative pathological type of the patients. The routine ultrasound and SWE examinations were conducted before operation, and the SWE parameters of the lesions, including the maximum (Emax), average (Emean), minimum (Emin), standard deviation (Esd) and whether the stiff rim sign presented or not at 1, 2 and 3 mm around the lesion were recorded. The SWE characteristics and differences in SWE parameters of the NML patients between two groups were analyzed, and the receiver operating characteristic curve(ROC) was plotted, and the area under curve (AUC), specificity and sensitivity were calculated. Results:There were statistically significant differences in age, lesion size, palpation, and whether menopause had crested of the NML patients between two groups (P<0. 01). All the lesions of the patients in two groups appeared as hyperechoic and irregular in shape. Compared with benign lesion group, the percentage of the patients with non-parallel, calcification and posterior echo attenuation in malignant lesion group was significantly increased (P<0. 01), and the percentage of the patients without blood supply was significantly decreased (P<0. 01). Compared with benign lesion group, the Emax, Emean, and Esd of the NML patients in malignant lesion group were significantly increased (P<0. 01), and the Emax, Emean, and Esd at 1, 2, and 3 mm around the lesion were all increased (P<0. 01). The stiff rim sign manifested as a circular or semi-circular red region around the lesions of the patients in malignant lesion group. Compared with benign lesion group, the percentage of hard rim sign of the NML patients in malignant lesion group was significantly increased (P<0. 01). Compared with inside the lesion, the Emin at 1, 2 and 3 mm around the lesion of the NML patients in benign lesion group and malignant lesion group were decreased(P<0. 01). The AUC of Emax at 1, 2 and 3 mm around the lesion were 0. 872, 0. 860, 0. 873 and 0. 866, respectively; the AUC of Emean were 0. 796, 0. 822, 0. 820 and 0. 815, respectively; the AUC of Esd were 0. 832, 0. 857, 0. 859, and 0. 842, respectively;the sensitivity and specificity of Emax inside the lesion were 85. 33% and 83. 13%, respectively; the sensitivity and specificity of Emax at 1 mm around the lesion were 82. 67% and 80. 72%, respectively; the sensitivity and specificity at 2 mm around the lesion were 78. 67% and 87. 95%, respectively; the sensitivity and specificity at 3 mm around the lesion were 80. 00% and 86. 75%, respectively; the specificity of Esd at 2 mm around the lesion was highest (93. 33%). Conclusion: The SWE parameters inside and around the lesion and the manifestation of stiff rim sign can provide the reference for the differential diagnosis of benign and malignant breast NML, and have good diagnostic performance. [ABSTRACT FROM AUTHOR]