Breast cysts 7mmx4mm are usually not serious if they are benign, but if they are malignant, they are a more serious condition. Breast cysts are categorized into simple cysts and cumulus cysts. Both are benign lesions. Simple breast cysts are mainly benign lesions caused by ovarian dysfunction. Breast cysts are formed due to ovarian dysfunction, decreased secretion of luteinizing hormone and increased secretion of estrogen, which leads to proliferation and shedding of breast epithelium, causing high dilatation and cystic changes in the lobular ducts and terminal mammary ducts of the breast. Clinically, simple cysts can be self-limiting, after 3 years or more, the lesions can stop, but sometimes they can continue and eventually lead to cancer, but the chance is very small. However, if a patient’s breast cyst is cancerous and relatively serious, it needs active surgical treatment. It is recommended that patients with breast cysts should consult a regular hospital and choose the appropriate treatment under the guidance of the doctor.