Clinicopathologic features and treatment of mammary duct ectasia MA Rong. Department of Breast Surgery， Qilu Hospital of Shandong University, Jinan 250012, China Abstract Mammary duct ectasia is of common inflammatory disease of breast. It is also called plasma cell mastitis, comedo mastitis, periductal mastitis, granulomatous mastitis and so on. Its primary basic pathologic change is mammary duct dilation. So it is called mammary duct ectasia is more rational. According to its different clinicopathologic features, it can be divided into four stages: duct dilation, inflammatory mass, abscess and fistula. We may treat this disease with different strategy in different stage.