Plasmacytoid mastitis and granulomatous mastitis are two sisters who appear to be inseparable. Plasmacytoid mastitis, which we abbreviate as “plasmacytoma” and PCM, is also called parareolar abscess, fistula, and ductitis. Granulomatous lobular mastitis, or GLM for short, is the most common of the ambiguous names for granulomatous mastitis, also known as idiopathic granulomatous mastitis. The two diseases are sometimes so similar in appearance that many physicians cannot distinguish between them and often refer to them collectively as plasma cell mastitis, diagnosing them as “plasma milk” when in fact many of them are “granulomas”, and even making obvious conceptual errors in the discharge summary documentation. The patient is even more confused and does not know which article to consult online. If you have seen the scattered rotten flesh-like lesions of sarcoidosis, you will understand how helpless local incision and drainage is. In order for you to distinguish between these two sisters, I briefly outline the following: 1. Age and breastfeeding: the age of onset of plasma milk is small, often unmarried girls, mostly in their 20s. Sarcoidosis is mostly menstrual, with onset within 3-5 years after childbirth, averaging over 30 years old, and related to breastfeeding disorders, hormonal drugs, etc. In terms of age, pulpy breast is the sister and sarcoidosis is the sister. Why are they called sisters? Because both belong to the same family of non-lactating chronic inflammatory diseases, both are related to the stimulation of their own substances (lipidic substances in the large ducts or milk in the alveoli), and both have autoimmune granuloma formation. It is only the degree and nature of the reaction that differs (irritant inflammation and hypersensitivity), with the sister being gentler and having a slightly slower onset. The sister is violent in nature, with sudden onset or lightning aggravation. The sister is a localized inflammatory disease, while the sister is a whole-milk inflammatory disease. Please see our three articles and pictures on “Pre-operative pulpy breast, preoperative granuloma and intraoperative changes”. 2. Etiology and pathogenesis: The granuloma is associated with nipple deformity, nipple entropion, splitting to form a place to hide dirt, not cleaned, the large duct under the nipple is twisted and blocked, the contents overflow, inducing plasma cells and lymphocytes to invade, gradually forming a small lump, followed by redness, breaking out of pus, although repeated, but can be temporarily relieved or short-term cure. Granuloma is a hypersensitive reaction to the previous accumulation of milk, the follicular lobules are the place of secretion and accumulation of milk, so the inflammatory reaction is centered on the lobules, scattered and widespread, not connected to each other, once the onset will not stop, late large lesions necrosis, fusion, redness, swelling, pus, one after another, can not be stopped. The first site: the pulpy breast is always around the areola, and the granuloma is centered on the glandular lobe. The first site is in each quadrant, away from the nipple, and if the granuloma is located near the areola, the two are very similar, and it is difficult to distinguish them for a while. 4. Main symptoms: Both of them are mainly manifested by lumps, pain, redness and swelling, breaking out of pus, systemic symptoms are not obvious, ultrasound and X-ray have no specific changes, and needle aspiration are all inflammatory cells. However, plasma breast lumps are small, painful and tolerable, and the onset is relatively slow, mostly small abscesses next to the areola, and only when secondary bacterial infection occurs do the abscesses become larger and form a single abscess cavity with normal surrounding glandular fat. The percentage of misdiagnosis of granuloma as cancer is higher if the initial mass is not painful. However, granuloma often suddenly becomes large or distant onset, with multiple abscesses, severe pain and deep impression, so the patient can remember the specific date of onset and the onset of the disease. 5. Difficulty of treatment: Although pulpy breast is prone to recurrence, it will not recur as long as the subpapillary lesion is completely removed, but it may affect papillary blood flow and partial necrosis occurs. When the lesion spreads to the whole breast, local excision will not help, the lesions are scattered and not connected to each other, and all of them can only be identified by the naked eye. The total excision must have a great impact on the appearance of the breast, so the doctor faces a difficult choice, the operation is time-consuming and laborious, and there is more bleeding, and the operation is much more difficult than the pulpy breast.