Carcinoma colorrectal serrado. Descripción histopatológica, inmunohistoquímica y molecular de un caso

Serrated adenocarcinoma is a recently described variant of colorectal carcinoma and is the end result of the molecular «serrated» pathway. The mutation of BRAF is the precursor lesion which gives rise to serrated lesions with a predisposition to genetic methylation and microsatellite instability. In this study we describe an adenocarcinoma of the right colon, with histological criteria for serrated adenocarcinoma: serrated epithelia, abundant cytoplasm, vesicular nuclei and absence of necrosis. Immunohistochemistry revealed loss of MLH1 immunostaining. PCR analysis confirmed high microsatellite instability, BRAF mutation and MLH1 methylation, thus demonstrating the presence of all the component alterations of the serrated pathway and their histological correlation with the defining criteria.