Anatomic pathology selected abstracts
March 2025—Invasive lobular carcinoma is characterized by loss of E-cadherin expression and CDH1 gene inactivation. The reliability and reproducibility of diagnosis for this tumor type is suboptimal and could be improved by better understanding the histomolecular and clinical heterogeneity of such tumors. The authors analyzed the relationship between the presence, type, or position of CDH1 mutations, E-cadherin expression, and clinicopathological features, including outcome, in a retrospective series of 251 primary invasive lobular carcinomas (ILC) with a median follow-up of 9.5 years. The mutational status of CDH1 (the gene encoding E-cadherin) was determined by RNA sequencing of frozen tumor samples. E-cadherin immunohistochemistry was performed with antibodies directed against the intracellular (clone 4A2C7) and extracellular (clone NCH38) domains.