Ductal invasive carcinoma arising within atypical microglandular adenosis in a patient with BRCA-1 mutation: A case report

Microglandular adenosis (MGA) of the breast is a benign lesion that may mimic invasive carcinoma and which has been proposed to be a potential precursor of a well defined subset of triple-negative and basal-like breast carcinomas, characterized by specific expression of both basal and luminal markers (positive for EGFr and luminal cytokeratins such as CK 8/18, negative for high molecular weight cytokeratins such as CK 5/6), with a crucial role played by p53 mutation as “driver mutation” in the multistep model of cancerization. When an invasive carcinoma arises in a background of MGA, it is possible to identify a clear multistep transition from conventional MGA to atypical MGA (AMGA), Ductal Carcinoma In Situ (DCIS) arising within AMGA and invasive carcinoma. This is the first histological case report of an invasive carcinoma arising within MGA and AMGA in a patient carrying a germline BRCA-1 mutation, recognized as one of the most important genetic alterations correlated with the development of triple-negative carcinoma.