Low-grade ductal carcinoma in situ of the breast, after total surgical excision, also has a malignant pathologic result. However, being in the early stage of the disease course, there is a possibility of curing the lesion. Breast cancer is one of the common malignant lesions of the breast, which is mainly divided into non-invasive carcinoma and invasive carcinoma according to the pathologic classification, of which, non-invasive carcinoma is also known as carcinoma in situ. And carcinoma in situ is further divided into other types such as ductal carcinoma in situ. According to the degree of differentiation of cancer cells, it is divided into three categories: low differentiation, middle differentiation and high differentiation, and the lower the degree of differentiation, the more obvious the degree of malignancy of the lesion. From the pathological findings, the patient was in the early stage of the disease, the lesion was relatively limited, and metastasis generally did not occur. However, the lesion was poorly differentiated and had a high degree of malignancy. For the current patient, surgical total resection is the main treatment option, and the pathology results will clearly indicate the malignancy status. However, surgical excision of the lesion has the potential to cure the lesion. In addition, choosing other treatment modalities according to the specific postoperative situation can improve the therapeutic effect and reduce the chances of lesion recurrence and metastasis.