There are many causes of nipple discharge. It can be physiological or pathological. It can be caused by diseases of the breast itself or by other endocrine diseases acting on the ducts of the breast. Among the common diseases of pathological nipple overflow are intraductal papilloma, papillomatosis, ductal dilatation, breast cancer, etc. Depending on the nature of the discharge, it can indicate different diseases. 1. Milk-like or gray thick fluid, physiological endocrine is more likely. 2.Purulent overflow, mostly considered inflammation of the breast. 3, yellow-green thick purulent-like, mostly chronic inflammation, ductal dilatation, chronic cystic hyperplasia. 4, bloody or brownish-yellow, most commonly intraductal papilloma, followed by malignant tumors. 5.Bloody fluid with variable mass, i.e., pressure mass with bloody fluid discharge, the mass becomes smaller or cannot be touched, mostly ductal papilloma (50%). 6.Bloody fluid with swelling has a high possibility of cancer (10%-50%). 7.If the age of bloody fluid is above 50 years old, 50% is cancer. 70% is cancer if it is above 60 years old. 8.Bloody overflow aged above 40 is mostly benign. 9.Plasmacythematous overflow with lump is more likely to be cancer. 10.Plasma watery or milk-like overflow, benign lesions are the majority.