Lobular carcinoma in situ (LCIS) is an uncommon condition in which abnormal cells form in the lobules or milk glands in the breast. LCIS isn't cancer. But being diagnosed with LCIS indicates that you have an increased risk of developing breast cancer.
LCIS usually doesn't show up on mammograms. The condition is most often discovered as a result of a breast biopsy done for another reason, such as a suspicious breast lump or an abnormal mammogram.
Women with LCIS have an increased risk of developing invasive breast cancer in either breast. If you're diagnosed with LCIS, your doctor may recommend increased breast cancer screening and may ask you to consider treatments to reduce your risk of developing invasive breast cancer.