Ductal Carcinoma In Situ (Synonyms: Intraductal Carcinoma, DCIS)

It is sometimes useful to think of the breast as a tree beginning with the trunk, proceeding through the multiple branches, and ending in small twigs and finally the leaves. In this analogy the trunk is the nipple, the branches are the large ducts, the twigs are the terminal ducts and the leaves are the lobules. We may then speak of "twig" disease (ductal disease) and "leaf" disease (lobular disease). Most of the important breast diseases are derived from twigs and leaves (small ducts and lobules) although a few breast diseases are more appropriately identified as "trunk and large branch" disease (derived from nipple and large ducts). Photo #1 shows two large ducts side by side. Top left is normal, bottom right is DCIS.

Comparison of normal duct and ductal carcinoma in situ. Click on the image for a larger view.

Ductal carcinoma in situ is small duct disease. In DCIS the normal duct cells are replaced by abnormal cancer cells of various types (See Photo #2 - #4). These three panels illustrate different types of ductal carcinoma in situ. DCIS cells can appear very similar to normal cells (grade I) or very abnormal (grade III) or somewhere in between (grade II). As long as these cells are contained within the duct they started growing in (that's what "in situ" means), they are practically never a biological threat to the individual as long as the appropriate treatment is undertaken. If untreated the risk of DCIS turning into invasive carcinoma is about 2-3% per year.

Paget’s Disease makes up less than 1% of all breast cancers.  It is a cancer that starts in the ducts of the breast and then involves the skin on the nipple.  It often presents as a rash on the nipple or areola with redness, oozing, itching, crusting, or burning and does not heal when treated like a dermatology problem such as eczema.  Paget’s Disease can only be determined with a biopsy that includes the nipple skin and underlying breast tissue.  If Paget’s disease is accompanied by a breast mass under the nipple the biopsy usually shows invasive duct carcinoma.  If there is no accompanying mass the lesion is likely to be non-invasive (i.e. DCIS only).

		DCIS, nuclear grade I. Click on the image for a larger view.
		DCIS, nuclear grade II. Click on the image for a larger view.
		DCIS, nuclear grade III. Click on the image for a larger view.