ESR1 and breast lobular carcinoma: It is also a fact that the surgical examination of the breast demonstrated the presence of an impalpable mass consistent with an infiltrating lobular carcinoma, whose morphological (Figures 3a, b, c) and immunoistochemical characteristics of cells were almost identical to those of the stomach: ER+ (Figure 3d), CK7+/CK20-; GCDFP15+.