Common breast cysts include simple cysts and cumulus cysts. Simple cysts are the most common among breast cysts. They are mainly caused by endocrine disorders that lead to ductal epithelial hyperplasia and increased cells in the ducts, resulting in duct extension, tortuosity, folding and necrosis of the duct wall at the folded area due to ischemia, forming cysts. Cysts are also called milk retention-like cysts, which are less common than simple cysts and are mainly due to blockage of a duct during lactation, causing milk stasis and formation of cysts. For breast cysts, the most definitive diagnosis is a mammogram. This can tell us whether the cyst is an echogenic nodule, whether there are attached tumors within the cyst, and whether there are irregularities and abundant blood flow in the cyst wall. The chance of malignancy in cysts is very small, and most of them we can observe and review the ultrasound regularly for comparison. If the cyst is large and has symptoms of compression, or if the ultrasound indicates local thickening of the cyst wall, rich blood supply, or if there is a tumor attached to the wall inside the cyst, or if the patient is under great mental stress, then surgery can be considered. Surgical treatment is divided into open surgery or minimally invasive. For young patients, cystectomy is performed, and if economic conditions allow, minimally invasive surgery such as McMurdoctomy is more effective: on the one hand, most of the cyst wall can be removed to prevent the formation of cysts again; on the other hand, the surgical scar can be basically ignored. Some places still use needle aspiration to treat cysts, which is undesirable; because the cyst wall has a secretory function, the cysts will grow again soon if the cyst fluid is aspirated and the cyst wall is not destroyed; moreover, repeated aspiration is easy to form infection and cyst separation.