▁also ▁required ▁for ▁their ▁different iation . ▁ ▁Im mun oh ist och em istry ▁ ▁Ess ential ▁for ▁the ▁different iation ▁and ▁surv ival ▁of ▁sympath etic ▁neur ons ▁and ▁chrom aff in ▁cells , ▁the ▁trans cription ▁factor ▁P HO X 2 B ▁is ▁highly ▁specific ▁for ▁the ▁peri pher al ▁autonom ic ▁nerv ous ▁system . ▁Ne uro bl asts ▁are ▁derived ▁from ▁sympath o ad ren al ▁line age ▁neural ▁cr est ▁cells ▁and ▁therefore ▁require ▁and ▁const itut ively ▁express ▁P HO X 2 B . ▁P HO X 2 B ▁imm un oh ist och em ical ▁st aining , ▁as ▁a ▁marker ▁of ▁neural ▁cr est ▁deriv ation , ▁has ▁been ▁shown ▁to ▁be ▁sensitive ▁and ▁specific ▁for ▁und iffer enti ated ▁ne uro blast oma , ▁en abling ▁identification ▁where ▁other ▁markers ▁fail ▁to ▁recognize ▁ne uro blast oma ▁among ▁various ▁different ▁small ▁round ▁blue ▁cell ▁tum ors ▁of ▁child hood . ▁ ▁The ▁di agnostic ▁utility ▁of ▁P HO X 2 B ▁st aining ▁extends ▁to ▁later ▁stages ▁of ▁different iation . ▁Its ▁strength ▁and ▁specific ity ▁can ▁detect ▁the ▁small ▁fo ci ▁of ▁ne uro bl astic ▁tum ors ▁met ast atic ▁to ▁the ▁b one ▁mar row , ▁an ▁identification ▁critical ▁for ▁determ ining ▁disease ▁st aging . ▁P HO X 2 B ▁st aining ▁also ▁over comes ▁frequent ▁obst acles ▁to ▁ne uro blast oma ▁detection ▁in ▁post - tre at ment ▁samples , ▁which ▁frequently ▁exhib it ▁dense ▁fib ros