Spontaneous nipple overflow, especially a small amount of liquid, not accompanied by breast pain, often can not cause the majority of female friends attention. In fact, nipple discharge is an early sign of breast disease or even breast cancer, and if it is not diagnosed and treated in time, the best time for surgery may be missed. What can cause nipple discharge? 1.Mammary duct dilatation: it is a benign disease and the most common cause of nipple overflow, which mostly occurs in the old people over 50 years old, and often develops in one side of the breast, and the overflow is often yellowish-brown liquid with small amount. 2, intraductal papilloma: a benign disease. It occurs mostly in women aged 40-50 years old, and the nipple overflows plasma or bloody fluid, which is intermittent or persistent, and the amount increases during menstruation. There is a possibility that 5-10% of the disease will become malignant, so surgery is also needed. 3, breast cystic hyperplasia: benign lesions. It is common in women of childbearing age. The nipple discharge is yellow-green, brown, bloody or colorless plasma-like. There are two characteristics of this disease: first, it is manifested as cyclic breast swelling and pain, which occurs or aggravates in the pre-menstrual period. Secondly, it is often accompanied by multiple breast lumps, which can be seen on one side or both sides, or confined to a part of the breast or dispersed in the whole breast, and the lumps can be reduced after menstruation. Breast cancer: some breast cancer patients have bright red or dark red nipple discharge. 45-49 years old and 60-64 years old are the two peaks of this disease. The disease starts slowly and is often accompanied by breast lumps, which are painless and gradually grow in size. Pressing on the lump will often result in an increase in the amount of fluid. How to distinguish between benign and malignant? In order to distinguish between benign and malignant lesions, a cytologic examination must be performed in a hospital. However, at home, you can make a preliminary judgment of benign or malignant tendency: 1. Age: Generally, menopausal women who are older than 50 years old are at a high risk of breast cancer and should be alerted. 2. 2, the color of the overflow: generally malignant overflow is bloody, so if the overflow is red or pink, it should cause high alert, and consult the doctor in time. Whether it is accompanied by breast lumps or not: nipple discharge of breast cancer is often accompanied by breast lumps at the same time. Whether it is a single milk duct or multiple milk ducts: Generally, the nipple discharge of breast cancer and intraductal papilloma is the discharge of a single milk duct, which needs surgery. In conclusion, nipple discharge is an important breast symptom, of which 10%~15% may be breast cancer. If you have symptoms, you should go to the hospital in time for cytological examination of the overflow smear or breast ductoscopy to make sure whether it is benign or malignant lesion and take appropriate treatment according to the result, so that you will not turn a small disease into a big one and delay the best time for treatment.