Lobular carcinoma in situ (LCIS) is a type of noninvasive breast
cancer that is confined to the cells lining the very end of the milk ducts
(lobules) in the breast. LCIS has some of the characteristics of cancer cells
but does not invade surrounding breast tissue or other structures.
LCIS is usually located in more than one area in the breast
(multicentric) and may be present in both breasts (bilateral). It is usually
discovered by accident, in the process of obtaining a biopsy of the breast for
another problem. It does not typically show up on a mammogram.
Experts disagree about whether LCIS is a preinvasive cancer or a
marker for the later development of an invasive cancer. A woman with LCIS has
an increased chance of having invasive breast cancer during her lifetime.