Lobular carcinoma in situ (10bularcarcinomainsitu, LCIS) is a controversial histological lesion at risk of developing into invasive breast cancer.In 1941, Foote and Stewart described LCIS as a non-invasive lesion originating from lobules and terminal ducts. It is therefore a precancerous lesion rather than a cancer. The diagnostic rate of the disease has improved due to the use of mammography, and 90% of the disease is premenopausal, suggesting a hormonal association. However, lobular carcinoma in situ and atypical lobular hyperplasia is a very resting lesion with a low cancer rate and a long cancer cycle (the average cancer rate among women diagnosed with lobular carcinoma in situ is 8%, and 50% of patients develop invasive cancer in 15-30 years). For general patients with lobular carcinoma in situ, only follow-up observation (semi-annual review is sufficient), puncture biopsy, local excision or endocrine therapy (consideration of tamoxifen before menopause to reduce the risk of invasive carcinoma can reduce the risk of breast cancer by about 50%. And postmenopausal patients may consider aromatase inhibitors, which have the same preventive value as tamoxifen, but with a lower risk of endometrial cancer). However, for special high-risk patients, such as those with a family history of breast cancer and BRCA1/2 mutation, bilateral total mastectomy combined with or without breast reconstruction may be considered.