The ducts of the breast are obstructed, causing ductal dilatation, epithelial atrophy of the duct wall, and the accumulation of lipid-like material and epithelial cell debris in the ducts corrodes the duct wall, resulting in a patchy infiltration of plasma cells in the fatty tissue surrounding the duct wall. There are different names for the different stages of development, such as ductal dilatation, acantholytic mastitis, chemical mastitis, etc. It is a “sterile” inflammatory disease of the breast. The symptoms are long and can recur. In the early stages, there may be pulpy fluid discharge from one or both nipples, sometimes forming small nodules with unclear borders under the nipple or areola. When the disease progresses, local symptoms such as redness, swelling and pain may appear, and lumps may appear around the areola or in the breast parenchyma, and skin adhesions, nipple retraction, local edema and enlarged axillary lymph nodes may also appear. Sometimes the lump gradually softens and forms an abscess, and after piercing it, it forms a fistula that does not heal for a long time. Treatment】 The dilated duct can be surgically removed when the nipple is drained. When local inflammation is obvious, antibiotics should be used to treat it and avoid incision and drainage. Abscess formation often penetrates on its own, forming a fistula that can persist for a long time. In this case, surgery should be performed to remove the fistula and its surrounding tissues. Currently, herbal treatment is also effective.