by Jason Wasserman MD PhD FRCPC
October 18, 2022
Lobular carcinoma in situ (LCIS) is a non-cancerous breast disease. Although LCIS is not a type of cancer, it is associated with an increased risk of developing breast cancer over time. The two types of breast cancer associated with LCIS are invasive ductal carcinoma and invasive lobular carcinoma. The increased risk applies to both breasts, not just the breast diagnosed with lobular carcinoma in situ. Another name for LCIS is lobular neoplasia in situ (LNIS).
The diagnosis of LCIS is usually made after a small sample of tissue is removed in a procedure called a core needle biopsy. LCIS is also commonly diagnosed after surgery is performed for another disease such as invasive ductal carcinoma or ductal carcinoma in situ.
There are two different types of LCIS, classic type and pleomorphic type. Your pathologist will determine the type based on how the abnormal cells look when examined under a microscope. Both classic and pleomorphic LCIS are associated with an increased risk of breast cancer but the risk is higher if the cells are pleomorphic.
Comedonecrosis is a term pathologists use to describe a group of tumour cells with necrotic (dead) tumour cells at the center of the group. Comedonecrosis is more likely to be seen in pleomorphic LCIS and it is associated with an increased risk of developing breast cancer.