Definition

A condition in which cells that look somewhat abnormal under a microscope are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. Intermediate-grade ductal carcinoma in situ tends to grow more quickly than low-grade ductal carcinoma in situ but not as quickly as high-grade ductal carcinoma in situ. It is also more likely than low-grade ductal carcinoma in situ to come back or become invasive breast cancer and spread to other tissues but not as likely as high-grade ductal carcinoma in situ. Also called grade II DCIS, grade II ductal carcinoma in situ, and intermediate-grade DCIS.