1.0 Overview Intraductal papilloma is a benign tumor that occurs in the epithelium of the breast ducts and is divided into central papilloma and peripheral papilloma. Central papilloma refers to papillomas occurring in the large ducts below the opening of the milk duct to the jugular; peripheral papilloma refers to multiple intraductal papillomas occurring in the terminal duct-lobular system (TDLU). The new classification also adds atypical papillomas, which refer to localized atypical epithelial hyperplasia with low-grade nuclei. Such intraductal epithelial hyperplasia may occasionally resemble atypical ductal hyperplasia (ADH) or small lesions of low-grade DCIS. Intraductal papillomas of the breast occur in women of any age after puberty, but are most commonly seen in women aged 40-50 years. 2.0 Diagnosis 2.1 Clinical manifestations 2.1.1 Symptoms: 1) Active or passive hemorrhagic, yellow plasma overflow, or plasma hemorrhagic overflow from the nipple, and watery overflow in a few patients; 2) Less than 30% of papillomas have palpable masses, and less than 20% of cases presenting with nipple overflow have palpable masses, which are mostly located in the areola area. 2.1.2 Physical examination: The basic physical signs are blood or plasma fluid overflow from the nipple when pressing the corresponding area of the breast, or palpable lump, and fluid overflow when squeezing the lump. 2.3 Ancillary examinations Mammography: the diagnostic rate of intraductal papilloma is very low. Ultrasound: Typical features include well-defined flat echogenic nodules or lobular flat echogenic cystic lesions with solid components, often with solid intraluminal echogenicity from ductal dilatation. Mammography imaging: shows smooth or irregular filling of the lumen associated with obstructed or dilated ducts. If the duct is completely occluded, the contrast material is seen to flow in a reverse direction. Mammography imaging is useful to clearly locate secretory ducts before surgical excision, but has drawbacks such as contrast allergy and the possibility of false positive and negative diagnosis. Ductoscopy is the predominant diagnostic method for intraductal papilloma, with an accuracy of more than 90%, and can help in surgical localization and identification of DCIS. 3.0 Treatment Intraductal papilloma is mainly treated by open surgery. Central papillomas located in the primary duct can be treated by local excision of the diseased duct. Segmental excision is appropriate for multiple papillomas below the secondary duct, peripheral papillomas and atypical papillomas. 4.0 Prognosis Those with a reasonable extent of surgical excision will not recur, but may recur in other ducts of the same or contralateral breast. If the lesion is missed by excision, recurrence of overflow may occur and require reoperation after mammography localization. The cancer rate of this disease reported abroad is 5%-33%, and the cancer rate reported in China is 5-15%.