During non-pregnancy and non-lactation periods, the flow of fluid when squeezing the nipple is called nipple discharge. Nipple overflow is one of the common symptoms of breast diseases. According to statistics, those who visit the doctor with nipple overflow as the first symptom account for 3% to 14% of breast diseases, and the incidence is second only to breast lumps and breast pain. If the nipple overflow is single nipple overflow, most of them are related to the following breast diseases: 1. Ductal dilatation of the breast: some patients suffering from this disease, the first symptom of early nipple overflow. The color of the overflow is mostly brown, a few are bloody; laboratory tests of the overflow can see a large number of plasma cells, lymphocytes and no tumor cells. The disease is more common in non-lactating or menopausal women over 40 years of age. The lump is often less than 3 cm in diameter and the ipsilateral axillary lymph nodes may be enlarged, soft and painful to the touch. If the lump is complicated by infection, the inflammatory manifestation of the lump is red, swollen, hot and painful. 2, intramammary duct papilloma: this disease is common in people aged 40 to 50 years old, 75% of the tumors occur in the area adjacent to the nipple, the tumor is very small, with a tip and villi, and there are many thin-walled blood vessels, so it is easy to bleed. The tumor cells can be found in the overflow of laboratory test. Sometimes patients can find cherry-sized lumps under the areola when they palpate the breast carefully, which are soft, smooth and active. 3. Cystic hyperplasia of the breast: it is more common in women of childbearing age. Some patients have yellowish-green, brown, bloody or colorless plasma-like nipple discharge, and no tumor cells are present in the discharge on laboratory examination. This disease has two characteristics: First, it is characterized by periodic swelling and pain in the breast, which often occurs or is aggravated during the premenstrual period, and is not minded by the patient in mild cases, but can affect work and life in severe cases. The second is that breast lumps are often multiple and can be seen on one or both sides, or can be confined to a part of the breast or scattered throughout the breast. The lumps are nodular in shape and vary in size, tough and not hard, not adherent to the skin, and not well defined from the surrounding tissues. 4.Breast cancer: Some patients with breast cancer have bright red or dark red nipple overflow, sometimes clear water overflow, colorless and transparent, occasionally viscous, and no trace of cancer cells can be found in the overflow after laboratory examination. The onset of the disease is slow. Patients may unintentionally find breast lumps, mostly located in the upper inner or upper outer limit, painless and gradually larger. In advanced stages, orange peel-like skin changes and satellite nodules appear at the lesion site. The axillary lymph nodes are enlarged, hard and fuse with each other to form a mass as the disease progresses. If double nipple discharge is present, it is likely to be due to systemic diseases, such as hemophilia, purpura, endocrine disorders, etc. The diagnosis can be confirmed by endocrinologists with relevant tests. In addition, some nipple overflow phenomena are physiological, such as within one year after stopping breastfeeding, most women still secrete a small amount of milk; in the middle and late pregnancy, some pregnant women can squeeze out a little light-colored colostrum from both breasts; in a few women, after a strong orgasm, due to high blood vessel congestion in the breast, breast distension and nipple erection, there will also be a short period of overflow; when women enter menopause, due to endocrine disorder, it will make Some women secrete a small amount of milk after menopause. These conditions are not pathological. There is also a phenomenon of pseudo-exudate, which is common in those with sunken nipples, due to the accumulation of epidermal cells in the sunken area of the nipple, causing a small amount of liquid-like bean curd-like exudate, which often has a foul odor. This is an inflammatory exudate that is not discharged from the milk ducts, so it is called pseudo-exudate. Once the sunken nipple is pulled out and the area is kept clean, the “overflow” will disappear. In conclusion, nipple overflow is an important breast symptom, 10%-15% of which may be breast cancer. If symptoms appear, you should go to the hospital for cytological examination of the smear. Near-infrared breast scan has a positive diagnosis rate of 80% to 95% for ductal lesions in the areola area, and ultrasound and mammogram also have a comparable accuracy rate. Selective lesion ductography is a commonly used test for nipple overflow and is of greater value in the differential diagnosis of benign and malignant with nipple overflow, it also provides the physician with accurate localization of the extent of surgical excision.