Breast cysts are also known as cystic hyperplasia of the breast. The biggest difference between it and breast hyperplasia is the coexistence of cystic hyperplasia and atypical hyperplasia of the breast, many people are not aware of breast cysts and think they are tumors and are worried about them, in fact, this is completely unnecessary. Breast cysts are mainly benign lesions caused by ovarian dysfunction. Breast cysts are formed due to ovarian dysfunction, reduced secretion of luteinizing hormone and increased secretion of estrogen in the body, resulting in proliferation and shedding of breast epithelium, causing high expansion and cystic changes in the lobular ducts and terminal ducts of the breast. Clinically, breast cysts can be self-limiting and can stop after 3 years or more, but sometimes they can continue to progress and eventually lead to cancer, but the chance is very small. Clinically, breast cysts can be divided into two types: simple cysts and cumulus cysts: 1. Simple cysts: simple cysts are the most common among breast cysts, mainly due to endocrine disorders causing ductal epithelial proliferation and increased cells in the ducts, resulting in duct extension, tortuosity, folding, and necrosis of the duct wall at the fold due to ischemia, forming cysts. Simple breast cysts are common in middle-aged women, with round or ovoid breast lumps as the main symptom, which can be solitary or multiple. The cysts may be solitary or multiple. In solitary cases, the lumps often grow rapidly and are easily confused with breast cancer, which often varies with the menstrual cycle and is accompanied by premenstrual breast swelling and pain. To make a definite diagnosis, mammography, ultrasound and needle aspiration cytology may be performed. If it is still ineffective after several punctures, or if epithelial hyperplasia or papillomatosis is confirmed by cytological or histological examination, surgery is appropriate. 2, cumulus cysts: cumulus cysts, also known as milk retention-like cysts, are less common than simple cysts and are mainly due to blockage of a duct during lactation, causing milk accumulation and formation of cysts. Breast cysts can be found in any part of the breast, but they are most common in the deep part of the breast and often occur during or after pregnancy and lactation. The main symptom of breast cysts is breast lumps, which are mostly round or ovoid, with smooth surface, cystic feeling, clear border, large mobility, and no adhesion to the skin. In case of secondary infection, inflammatory reactions such as local redness, swelling, heat and pain can be seen, and enlarged lymph nodes can be palpated in the ipsilateral axilla. If the cyst is large, has a long history of disease, or has recurrent infections, it is advisable to remove the cyst surgically. Breast cyst is a common gynecological disease, the treatment is relatively simple, generally does not produce serious consequences, women are completely unnecessary worry, as long as timely detection, active treatment, can be completely cured.