What defines Lobular Carcinoma in situ?

Lobular Carcinoma in Situ (LCIS) is primarily characterized as an incidental finding during biopsies. This type of carcinoma does not typically present as a palpable mass or distinct symptoms; instead, it is often discovered unexpectedly while examining breast tissue for other reasons, such as during a biopsy for a suspicious lesion. It is categorized as a marker of increased risk for developing breast cancer later rather than an immediate threat.

The nature of LCIS means that it does not usually lead to areas of calcification, which are more commonly associated with certain types of ductal carcinoma in situ (DCIS). While it can sometimes present bilaterally, LCIS is not defined by unilateral findings. Additionally, it is not characterized as more aggressive than Noncomedo Ductal Carcinoma; rather, it generally has a more indolent course. Understanding these characteristics helps clarify why recognizing LCIS as an incidental finding is critical in screening and risk assessment for breast cancer.