PIK3CA and breast lobular carcinoma: The frequency of CDH1 mutations in PIK3CA-AKT1-PTEN-MT was higher in lobular than in non-lobular carcinoma (73.5 vs. 6.8%), although frequency of CDH1 mutations remained positively associated with PIK3CA-AKT-PTEN-MT after lobular cases were excluded from the analysis.