Furthermore, previous descriptions of epithelioid morphology in PXAs do not specify glioneuronal differentiation defined in these three cases by synaptophysin immunohistochemistry, notwithstanding the fact that synpatophysin immunopositivity does not always strictly equate with neuronal differentiation, such as in the examples of pilomyxoid astrocytomas [33] and choroid plexus papillomas [34]. This evidence concerns the gene SYP and choroid plexus papilloma.