Abstract. Background: The Japanese Association of

Mammary Ductoscopy proposed a classification system based on the objective endoscopic appearance of intraductal lesions. This system includes four categories: solitary polypoid, multiple polypoid, superficial, and combined type. However, previous studies did not adequately compare endoscopic findings with histological findings and the prognosis. Patients and Methods: One hundred and ten patients with nipple discharge who had intraductal tumors were identified by mammary ductoscopy, and 25 breast cancer patients were identified from our database of records between 2001 and 2008. The clinicopathological data and outcomes of these patients were then reviewed. Results: Lesions in 25 breast cancer patients comprised 12 polypoid solitary type, 3 polypoid multiple type, 5 superficial type, and 5 combined type. Polypoid type showed a low sensitivity on cytologica