ATRX/DAXX in EUS-FNB Specimens of Pan-NETs

Immunohistochemistry will be performed using an Autostainer Leica (Leica Biosystems) according to the manufacturer's instructions. Four μm formalin-fixed paraffin-embedded sections will be immunostained with antibodies for Cytokeratin AE1/AE3 (AE1-AE3, 1:100 dilution, Novocastra/United Kingdom) Chromogranin A (DAK-A3, 1:2500, Dako/Denmark), and Synaptophysin (27G12, 1:100, Novocastra), Ki67 (MIB1, 1:100, Dako/Denmark), ATRX (1:400, Sigma-Aldrich), DAXX (1:200, Sigma-Aldrich). After antigen retrieval, immunostaining will be performed in an automated Bond instrument (Vision-Biosystem, Leica, Milan, Italy) using a sensitive peroxidase-based 'Bond polymer Refine' detection system.