OTX‐2 Expression as a Diagnostic Marker for Choroid Plexus Tumors

Choroid plexus tumors are neuroepithelium-derived tumors arising in the ventricles of the central nervous system. They are commonly seen in childhood and correspond to low rates in all central nervous system tumors. Due to their rareness and similar histomorphologic features to other tumors, their diagnosis might be challenging. Here, we used the OTX-2 antibody to evaluate the diagnostic role of OTX-2 expression in choroid plexus tumors. We performed a retrospective review of 34 patients operated for choroid plexus tumors in our center between 2011 and 2023. Additionally, as different tumor types are also arising in the ventricles, we selected five cases each of AT/RT, germ cell tumor, ependymoma, and metastatic adenocarcinoma from the pathology archive. Immunohistochemistry conditions were adjusted for each specific antibody based on the manufacturers' recommendations for concentrations and antigen retrieval/blocking. OTX-2, S-100, and transthyretin antibody staining was performed on sections from each case.