Context: - Lobular carcinoma in situ (LCIS) refers to a neoplastic proliferation of cells that characteristically shows loss of E-cadherin expression and has long been regarded as a risk factor for invasive breast cancer. Long-term outcome studies and molecular data have also implicated LCIS as a nonobligate precursor to invasive carcinoma. In the past few decades, pleomorphic and florid LCIS have been recognized as morphologic variants of LCIS with more-aggressive histopathologic features, less-favorable biomarker profiles, and more-complex molecular features compared with classic LCIS. There is still a lack of consensus regarding certain aspects of managing patients with LCIS.
Objectives: - To review recently published literature on LCIS and to provide an overview of the current morphologic classification of LCIS, recent molecular advances, and trends in patient management.
Data sources: - Sources included peer-reviewed, published journal articles in PubMed (US National Library of Medicine, Bethesda, Maryland) and published guidelines from the National Comprehensive Cancer Network (Fort Washington, Pennsylvania).
Conclusions: - Lobular carcinoma in situ represents a marker for increased risk of breast cancer, as well as a nonobligate precursor to invasive carcinoma. Morphologic variants of LCIS-florid and pleomorphic LCIS-are genetically more-complex lesions and are more likely to be associated with invasive carcinoma. Further investigation into which molecular alterations in LCIS are associated with progression to invasive carcinoma is needed to help guide medical and surgical management.