HER2-positive colorectal carcinoma with invasive micropapillary component

Colorectal cancer (CRC) is one of the most common and deadliest forms of cancer worldwide. Molecular subgroups are increasingly relevant for prognosis and therapy. In addition to established markers such as RAS, BRAF and MSI, HER2 is also coming into focus as a therapeutic target. Particularly rare histological variants such as invasive micropapillary carcinoma (IMPC) raise new questions. A recent case report from Japan describes for the first time a patient with HER2-positive colorectal carcinoma and a micropapillary component. This article summarizes the available data and discusses the clinical significance of this constellation.