l The nature of the overflow is divided into: bloody, plasma, lactic and purulent. l Bloody nipple overflow: the most common is intraductal papilloma, followed by breast cancer, ductal carcinoma is the most common among breast cancers, and a few breast hyperplasia can also be seen as nipple overflow. The general surgery department of the 309th PLA Hospital, Zhang Bo 1. if the bloody nipple overflow is accompanied by a single mass and the mass is located outside the areola, breast cancer is more likely; 2. if the mass is not accompanied by a mass, but sand-like calcification can be seen in the mammogram, breast cancer is more likely; 3. no breast cancer cells are found in the smear cytology, but breast cancer cannot be excluded; 4. fine needle aspiration is performed on the bloody nipple overflow with a mass. The best method to diagnose breast cancer is cytology. 5. Ductal iodine oil imaging of bloody nipple discharge has little significance in the differential diagnosis of breast cancer and intraductal presenting cephaloma. 6. Bloody nipple discharge occurs in men or women over 40 years of age, and breast cancer is more likely to occur in single breast with short duration. l Plasmacy is the most common among nipple discharge, accounting for about 50%. Bloody is the second most common, accounting for about 30%. Milk and pus are rare.