In these cases, negativity for keratin and site-specific transcription factors for neuroendocrine tumors as well as positivity for tyrosine hydroxylase (except for non-functioning HN PGLs) and GATA-3 immunohistochemistry seem to be valuable biomarkers to confirm the diagnosis of a PCC/PGL in most cases, as recently reviewed [20]. The gene discussed is TH; the disease is neuroendocrine neoplasm.