Background and Objectives: The diagnostic value of Contrast-Enhanced Spectral Mammography (CESM) for identifying of atypical non-mass lesions in the breast remains unknown. CESM application to differentiate benign and malignant non-mass breast lesions. Methods: A retrospective analysis was conducted on 94 female patients who underwent CESM. Lesions were classified using the Breast Imaging Reporting and Data System (BI-RADS) based on CESM low-energy images, categorizing 4A and below as benign, and 4B and above as malignant. The inter-and intra-observer consistency of BI-RADS classification was first evaluated. The diagnostic efficiency of BI-RADS classification in determining the nature of atypical non-mass breast lesions was assessed using pathology results as the gold standard. The differences in enhancement levels on subtraction images between benign and malignant groups were compared. Results: The inter-observer intra-class correlation coefficient (ICC) for BI-RADS classification was 0.906 (95% CI = 0.885-0.954, P < 0.001), and the intra-observer ICC was 0.932 (95% CI = 0.911-0.968, P < 0.001). BI-RADS classification identified 40 cases as 4B and above, and 54 cases as 4A and below, with an accuracy of 80.9% ((30+46)/94), sensitivity of 78.9% (30/38), specificity of 82.1% (46/56), positive predictive value of 75.0% (30/40), and negative predictive value of 85.2% (46/54). Conclusion: CESM has acceptable application value in distinguishing between benign and malignant atypical non-mass breast lesions. The high consistency between and within observers suggests good reproducibility of BI-RADS classification, providing an important basis for evaluating the extent and nature of atypical non-mass breast lesions and aiding in preoperative clinical decision-making.