Figure 1. Left breast cranio-caudal (A) and mediolateral-oblique (B) mammography depicting a lobulated well-defined mass measuring 80 mm in maximum diameter; (C) High nuclear grade, pleomorphism, and significantly increased mitotic activity in this pleomorphic lobular cancer arranged in a rather solid growth pattern (HE stain); (D–F: left to right) ER, PR and HER2 immunonegativity; (G) Ki67 Labelling Index estimated approximately at 50%; (H) E-Cadherin loss of expression and (I) beta-catenin aberrant expression in support of a lobular phenotype; (J) GATA3 nuclear immunoreactivity in the entire neoplastic population; (K) p53 aberrant immunoexpression pattern indicative of an underlying TP53 genetic aberration. Note that TP53 is the most frequently mutated driver gene in TNBC, with BRCA1 and TP53 deficiencies potentially leading to genomic instability and replicative drive [3].