A carcinoma entirely confined to the mammary ducts. It is also known as DCIS. There is no evidence of invasion of the basement membrane. Currently, it is classified into three categories: High-grade DCIS, intermediate-grade DCIS and low-grade DCIS. In this classification the DCIS grade is defined by a combination of nuclear grade, architectural growth pattern and presence of necrosis. The size of the lesion as well as the grade and the clearance margins play a major role in dictating the most appropriate therapy for DCIS. The disease is MONDO_0005023 (ductal breast carcinoma in situ). Also known as: DCIS, carcinoma in situ of mammary duct, ductal carcinoma in situ, ductal carcinoma in situ (DCIS), ductal carcinoma in situ of breast, ductal carcinoma in situ of the breast, intraductal breast carcinoma, intraductal carcinoma.