Paramammary gland is a breast tissue other than the normal breast, also known as ectopic mammary gland, polymammary gland disease or polymammary malformation, which is a congenital developmental abnormality that occurs in the anterior axillary line and can occur in both sexes, but is more common in women. In the sixth week of embryonic life, six to eight pairs of mammary gland primordia produced by ectodermal epithelial tissue begin to appear on the breast line (the line between the top of the axilla and the pubic bone). If these mammary gland primordia do not disappear completely. A few of the primordia continue to develop or develop incompletely and become parametrial. The peak age of onset is between 25-45 years. It is considered to be related to changes in hormone levels in the body, especially the stimulation of estrogen, progesterone and prolactin. With low hormone levels before puberty, the parammary gland lumps are not obvious, while with high hormone levels during puberty and fertility, the parammary gland is regulated by hormones and proliferates, and the onset decreases after menopause. In short, high estrogen is the main cause of paramammary gland development. Parammary gland adenopathy, commonly known as cystic hyperplasia of the paramammary glands, is formed in the parammary glands. It manifests as premenstrual swelling and discomfort in both armpits that varies with the menstrual cycle and even affects the shoulders and upper limbs. Parammary glands can also form fibroids or even malignant tumors (parammary adenocarcinoma), so it is important to pay sufficient attention to them. The cancer rate of the parammary gland is generally lower than that of the normal breast and is extremely rare. The incidence of adenocarcinoma of the parametrial breast is reported to be 0.2-0.6% of all breast cancers in foreign countries. Because of the special location of the parametrial gland, the lymphatic system and blood vessels are very rich. The lymphatic system and blood vessels are very rich. The 5-year survival rate is much lower than that of breast cancer. The 5-year survival rate of parametrial breast cancer is 41.7%. Therefore, the 5-year survival rate of parametrial cancer is 41.7%. Therefore, paramammary gland disease should be taken seriously in clinical practice. Parammary gland disease is mainly associated with an increase in the number of localized bulges in one or both axillary tissues, and lumps can be found in the axillary area, often accompanied by swelling and stinging pain in the axilla associated with the menstrual cycle. When the axillary lumps are large, the summer dressing affects the aesthetics. Physical examination: limited bilateral (unilateral) axillary bulge, lumpy, nodular granular masses can be palpated in bilateral or unilateral axillae; tough or hard texture, smooth surface or nodular, granular, variable size, unclear border, no adhesion with skin and surrounding tissues, movable. The masses are painful to palpation, with occasional traces of nipple on the surface of the axillary masses, and may be accompanied by nipple overflow during lactation. The axillary lymph nodes are not enlarged. The diagnosis of axillary paronychia is based on: ① Periodic axillary swelling and pain; most patients feel swelling and pain in the axilla before menstruation, during pregnancy or during lactation, while some patients never feel any discomfort. The axillary masses are round or flat, varying in size, mostly around 3.5 to 6.0 cm, and are found in more than 90% of patients after marriage and childbirth. The lump is soft to the touch, with a sense of striations or gland-like masses; most of them have the discomfort of squeezing when the upper limb of the affected side is drooping. The nipple can be found on the surface of the lump, and is the size of a grain of rice, mostly sunken, with an inconspicuous areola, and because of its small size, it often requires careful examination to find traces of the nipple. In a few patients, nipple overflow is found during lactation. ④ Ultrasound and mammography reveal axillary mammary gland-like manifestations that are not connected to the normal breast. This can improve the diagnostic accuracy of axillary parametrial glands and their diseases, and differential diagnosis of changes caused by local fat thickening in the axilla alone. Ultrasound: Axillary paramammary glands are superficially located, long oval or long shuttle-shaped, with poorly defined borders, and located in the subcutaneous fat layer; the echogenicity is similar to that of normal breast tissue and is moderately echogenic, with no or mildly attenuated posterior echogenicity. Mammography: Axillary parametrial glands are usually characterized by an increased density in the axilla that is not connected to normal breast tissue and resembles a normal breast gland. Treatment of axillary parametrial glands: ① Conservative treatment: Smaller glandular axillary parametrial glands are soft to the touch, with no or mild periodic swelling and pain, and although they increase in size and pain during pregnancy and lactation, they shrink afterwards and the pain disappears; ultrasound or mammography suggests only a small amount of glandular tissue, with no obvious masses or other abnormal signs; if they do not affect physical activity and aesthetics, they can be followed up without any treatment. If the symptoms of periodic swelling and pain in the axilla are obvious, Chinese herbal medicine can be given to dredge the liver and regulate the qi, activate blood circulation and remove blood stasis, disperse nodules and eliminate lumps. Surgical treatment: Patients with glandular parametrium or complete parametrium, abnormal masses suspected of malignancy, large parametrium gland or areola affecting appearance should be surgically removed and routinely sent for pathological examination. Surgical precautions: The incision direction should be consistent with the skin pattern, so that the scar is not obvious after healing. In recent years, some units also use lipolysis and liposuction technology to complete the surgery of parametrial breast.