The chronic mastitis can be caused by acute mastitis that is not effectively treated in a timely manner, or it can start as a chronic inflammatory process. It is common for non-lactating mastitis. Plasmacytoid mastitis is a common cause of chronic mastitis. Plasmacytoid mastitis is named for the large number of plasma cells that infiltrate the tissue surrounding the inflammation. The cause is a dysfunctional secretion of the epithelium of the breast ducts and the accumulation of lipid-like secretions in the milk ducts. The chemicals produced by decomposition irritate the surrounding tissues and cause inflammation, especially in the large ducts at the nipples and areola, where patients tend to have nipple depressions. Sometimes the inflammation can become acute and become an abscess, and the pus often contains powder-like material, so it is also known as “acne mastitis”. The lumps are hard, with unclear borders, and can be painful to the skin, and they do not easily form abscesses or dissipate. There is no typical localized redness, swelling, heat, or pain in the breast, and there are no obvious systemic symptoms such as fever, chills, or fatigue. When there is an acute attack of chronic mastitis, redness, swelling and pain may appear. The lump is often mistaken for a tumor because of its hardness, low skin temperature and mild pain. The principle of treatment is to clear heat and detoxify the body, pass the milk and reduce swelling. Oral Chinese medicine such as dandelion and wild chrysanthemum can be taken, and adult medicine such as Xinhuang tablet. Local physical therapy and hot compress are feasible. At the same time, breast should be lifted by bra. If it is plasma cell mastitis, surgery can be done to remove the dilated duct and the inflamed gland where it is located when the nipple is drained. The actual abscess is usually not easily formed in chronic mastitis, once it is formed, it should be incised and drained, the principle is the same as the abscess incision and drainage in acute mastitis. If the acute mastitis is prolonged during the lactation period, it should be treated as a return to the breast. In case of plasmacytic mastitis, the abscess often penetrates on its own and forms a fistula, which may not heal for a long time. In this case, surgery should be performed to remove the fistula and its surrounding tissue. The patient has to be prepared and the doctor has to be patient. (2) Patients are advised not to change doctors frequently, but to choose a doctor who will be dedicated to your care. (3) For long-term breast inflammation, systemic treatment (such as intravenous fluids to reduce inflammation) is often ineffective and local treatment is more important. However, if systemic manifestations such as fever are present, systemic treatment is also needed. It is best to perform pus bacterial culture plus drug sensitivity test and select sensitive antibacterial drugs. (4) Chinese medicine can play a role in the treatment of chronic mastitis. (5) Local treatment includes: external application of anti-inflammatory drugs (such as Jinhuang San, 25% magnesium sulfate wet and hot compresses, etc.), physical therapy, puncture and drainage or incision and drainage. (6) After mastitis forms an abscess, it should be incised and drained, and the drainage should be unobstructed and adequate. Allow the skin incision of the breast to heal after the internal breast has gradually improved. (7) For those whose breast inflammation has been limited after effective non-surgical treatment but cannot completely subside, surgical excision of the lesion may be considered.