Comedocarcinoma is one kind of breast cancer which is most commonly very early-stage  which demonstrates central necrosis. It is a usually a type of ductal carcinoma in situ. Comedo carcinomas are usually non-infiltrating and intraductal tumors. However, there have been accounts of comedocarcinoma which has then diversified into other cell types and developed into infiltrating (invasive) ductal carcinoma. Recurrence and survival rates differ for invasive breast cancer which has originated as comedocarcinoma compared with other types of cancer cells.
The duct will have characteristic necrotic tissue with calcification that feels cord-like. Squeezing the duct will yield inspissated material that is cheese-like and similar in consistency to toothpaste.