1, Plasmacytoid mastitis is the accumulation and overflow of fatty material in the ducts of the breast, causing chemical irritation and immune response around the ducts, resulting in a large number of plasma cell infiltrates, hence the name plasmacytoid mastitis. 2. It is not a bacterial infection, but can be secondary to bacterial infection. 3.It is not related to pregnancy and lactation and does not develop during lactation. 4, Inflammation may recur and may form chronic inflammatory masses that break down and form fistulas that do not heal for a long time. 5, The onset is related to nipple dysplasia: nipple entropion, nipple splitting, etc. 6. The lesions are mostly near the areola, locally red and swollen, and painful. Usually no fever. 7.Conservative treatment: anti-inflammatory, local hot compress, Chinese medicine, etc. 8.Puncture or incision and drainage when there is more pus, chronic inflammatory masses can be removed.