Lobular Carcinoma In Situ

In a previous section on ductal carcinoma in situ we used the analogy of a tree with trunk, branches, twigs and leaves to correspond to parts of the breast (nipple, large duct, terminal ducts and lobules). To carry on this analogy, lobular carcinoma in situ is an example of a pure "leaf" disease. The lobular cells are replaced with abnormal cells, and analogous to DCIS, they are contained within the boundary of the lobule and are not an immediate biologic threat. An example of lobular carcinoma in situ can be seen in the right lower panel of the picture below. Whereas DCIS is important because it is a first step in the direction of invasive ductal carcinoma (invasive cancer) LCIS is important for two reasons. LCIS is the first step in the direction of invasive lobular carcinoma however it usually takes longer to develop invasive cancer than with DCIS, and the percentage of individuals with LCIS that will develop invasive carcinoma is much smaller than with DCIS. Regarding women with LCIS, approximately 1% per year will develop an invasive breast cancer. LCIS is also important because it is "marker" lesion. That is LCIS identifies women whose breast tissue overall is at higher risk than normal to develop a tumor (in any location and in either breast). In most patients with DCIS almost all of the risk is in the same region of the same breast that was biopsied.

Lobular Carcinoma in Situ. Click on the image for a larger view.