a form of carcinoma derived from the epithelial lining of ducts, especially in the breast, where most carcinomas arise from ductal epithelium; the neoplastic cells proliferate in irregular papillary projections or masses, filling the lumens, that are solid, cribriform, or centrally necrotic; intraductal carcinoma is a form of carcinoma in situ because it is contained by the ductal basement membrane; when it invades surrounding stroma or metastasizes, it is referred to as ductal carcinoma.
