Lobular carcinoma in situ of the breast is cancer. Lobular carcinoma in situ is a non-invasive malignant tumor originating from the lobules and terminal ducts of the breast. The incidence of lobular carcinoma in situ is relatively low, and the onset of the disease is relatively insidious, and it can be seen in women of any age. The cause of the disease is complicated and related to hormone level, heredity, environment and other factors. There are no obvious features in the clinical manifestations of the patients, and multicenter and bilateral diseases are the most common. X-ray, ultrasound and MRI examinations can assist in the diagnosis. In terms of treatment modalities, it is still controversial, but local excision is the mainstay. The prognosis of lobular carcinoma in situ is usually good. Patients are advised to consult the breast department of regular hospitals for timely treatment. It is also recommended that women over 40 years of age should undergo regular breast checkups.