Intraductal papilloma is a benign papilloma that occurs in the ductal epithelium of the breast and can occur in women of any age after puberty, but is more common in menstruating women, especially in women aged 40 to 50 years. As a common benign breast tumor, the main clinical manifestation of intraductal papilloma is nipple discharge, which may occur when the breast is squeezed, but is more likely to be spontaneous. The overflow may be continuous or intermittent. The majority of patients present to the hospital with a complaint of nipple discharge. The color of the overflow is related to the length of time it remains in the ducts after bleeding – the longer it remains in the ducts after bleeding, the more soy-like the color of the overflow; if the overflow is bright red, the color is bright red; if the bleeding is minimal and mixed with other overflows, the color is lighter. The color is lighter. The amount of blood spilled is related to the extent and depth of the lesion in the duct. Sometimes the overflow is bloody, sometimes mucus, sometimes more, sometimes less, or even no overflow at all. Patients often seek medical attention by chance when they find blood in their underwear or bras. Most cases are not associated with pain. In a few cases, when the tumor is large and obstructs the breast ducts, it can produce pain and lumps, which will become smaller and the pain will be relieved to varying degrees as the accumulated blood and fluid is drained. Since the tumor of intraductal papilloma is very small, it cannot be palpated in most cases, and only about 20% of patients can find the lump at the nipple areola. The masses are nodular or striated, soft, and generally small, with a diameter of 0.5 to 1 cm, or occasionally more than 2 cm, and when gently pressed, bloody or coffee-like fluid can escape from the nipple. The characteristic manifestations of intraductal papilloma are mainly three: one is nipple discharge, especially bloody discharge; the other is pain, which is relieved with the discharge of accumulated blood and fluid; the third is a mass, nodular or striated, mostly in the nipple areola area. Classification of intraductal papilloma: Based on the number of lesions and the location of the lesions, intraductal papilloma can be divided into solitary, i.e., large intraductal papilloma, and multiple, and small and medium intraductal papillomas. Large intraductal papillomas originate from the abdominal region of the milk ducts and are mostly solitary, located in the subareolar region, accounting for 75% of all cases; small and medium ductal papillomas originate from the terminal ducts of the breast and are often multiple, located in the peripheral region of the breast, with unclear borders and uneven texture, accounting for 25% of all cases. In general, single large intraductal papillomas are more likely to overflow, while multiple small and medium intraductal papillomas are less likely to overflow. There are different views on whether intraductal papilloma of the breast is carcinogenic. Some people have followed up 427 cases of intraductal papilloma for 1-22 years, and only 2 of them were cancerous, so the cancer rate of this disease is considered to be very low. However, others have a different view – a set of statistics shows that this disease has a malignant rate of 5% to 10%, so it is called “precancerous lesion” and has been given sufficient attention. Although there are controversies about the issue of cancerous papilloma in breast ducts, there is one point that most people agree, that is, single papilloma in large ducts is rarely malignant, because single intraductal papilloma is well differentiated, its origin is independent, not related to papillary carcinoma, and has no tendency to become malignant; while multiple papillomas occurring in the terminal ducts of breast, with active cell proliferation, are prone to malignant changes, so they are considered as precancerous lesions.