Novel Recognition of HER2 Amplification in Enteroblastic Colonic Adenocarcinoma. Diagnostic Clues and Future Perspectives

Enteroblastic differentiation in sporadic colonic adenocarcinoma was a rare event that lacks to be fully elucidated. It was characterized by an aggressive biological behavior, with early metastatic spread and poor prognosis. Diagnostic clues and molecular features were not completely elucidated so far. Histological features including tubulo-papillary architecture, cleared neoplastic cells, fetal oncoproteins expression were diagnostic requirements. We describe a new case of enteroblastic colonic adenocarcinoma (CAED) in the sigmoid, exhibiting small intestinal phenotype, higher stage at diagnosis and early liver metastases. At molecular level, CAED shared both TP53 gene mutation and beta-catenin nuclear translocation with conventional colonic adenocarcinoma. Altered human epidermal growth factor receptor (HER) 2 signaling has been described in a small subset of conventional colonic adenocarcinoma. At best of our knowledge our report represents the first immunohistochemical recognition of HER2 gene amplification in CAED. Given its aggressive clinical behavior, clinicians should be aware of the possible HER2 amplification, that could point toward further treatment options.