Abstract: Objective: To study the pathologic characteristics and differential diagnosis of intracystic papillary carcinoma(IPC) of the breast.Methods: The clinical and pathological findings of one case of IPC of the breast were reported and the differential diagnosis was discussed with review of the literature.Results: The tumor was a gross and irregular nodule,gray-white color and intracystic on cut surface.The papillary was seen inside the capsule wall microscopically.The tumor was constituted of big papilla and the papilla contained fibrovascular stalks.One or more layers of malignant cells laid alignment,the cells were of high columnar form and shuttle form,and no mitotic figures detected.Immunohistochemically,the tumor cells were positive for CK7,EMA,E-cad,p53 and Ki-67,but negative for SMA,S-100 protein,actin,ER,PR,c-erbB-2,p63,CK (34βE12) and CEA.Conclusions: IPC is a rare epithelial tumor.Its varied histology and morphology often lead to misdiagnosis.It must be distinguished from papilloma,myoepithelial tumor and various metastastic papillary carcinomas in making a diagnosis.