Plasmacytoid mastitis. It is a chronic inflammatory disease of the breast based on ductal dilatation and plasma cell infiltration. Patients with this disease often have a history of nipple indentation and the disease occurs mostly during non-lactation periods. The disease has a long course and can be recurrent. In the early stages, there may be pulpy fluid drainage from one or both nipples, sometimes forming small, ill-defined nodules under the nipple or areola. When the disease progresses, local symptoms such as redness, swelling and pain may appear, and a lump may appear around the areola or in the breast parenchyma. Sometimes the lump gradually softens and forms an abscess, which can penetrate and form a long-lasting fistula. The incidence of this disease has increased significantly in recent years and is a difficult disease of the breast area, second only to breast cancer in terms of damage to women. We have used a combination of Chinese and Western medicine to treat plasmacytic mastitis with satisfactory results. Chinese medicine is applied to clear heat and dampness, benefit Qi and nourish blood, and other treatment principles to support the righteousness and drive away the evil, together with external application of Chinese ointment Ruyi Jinhuang Ointment and physical therapy to shrink the lump to the point of disappearance, heal the fistula, confine the inflammation within 7-15 days, expose the fistula under color ultrasound, and then perform fistula removal and nipple orthopedic surgery, followed by Chinese medicine for 2-3 months after discharge to prevent recurrence and completely cure the disease. The treatment method we use is simple, with a small scope of damage, less pain, less scarring, and complete treatment, and it keeps the breast shape intact and maintains its normal physiological function.