Invasive lobular carcinomas

Invasive lobular carcinoma (ILC) is the second most common type of invasive breast cancer after nonspecific invasive carcinoma (NSCLC). Its frequency is estimated to be between 1 and 15% of invasive breast tumors. It is a particular clinico-pathological entity characterized by a difficult clinical and radiological diagnosis. The diagnosis is anatomopathological. It is often associated with lobular carcinoma in situ (LCIS). The latter is part of non-invasive lobular neoplasia (NLNI) which is a lesional spectrum of atypical epithelial proliferation originating at the ductulo-lobular end unit. The latest 2019 WHO classification of breast tumors recognizes a new subtype of CLIS which is CLIS florid.