Warren M, et al. - The intent of this research was to shed light on the utility of Phox2b in pediatric tumors. It was deduced that Phox2b was a specific and sensitive marker for peripheral neuroblastic tumors (pNT) and pheochromocytoma/paraganglioma (PCC/PG). It was found to be particularly useful for determining that neuroblastoma undifferentiated (NB-UD) often lacked tyrosine hydroxylase (TH). A composite rhabdomyosarcoma/neuroblastoma of neural-crest origin was presented.