An interesting phenomenon that raises questions about the distinction between paragangliomas and epithelial NETs is the existence of rare “gangliocytic PGLs” and “cauda-equina type PGLs” that are positive for keratins [2]; while most of these have not been assessed with either GATA-3 or tyrosine hydroxylase immunohistochemistry (see below), an endobronchial gangliocytic PGL showed positivity for tyrosine hydroxylase expression [35]. This evidence concerns the gene TH and paraganglioma.