Esthesioneuroblastoma is not a member of the primitive peripheral neuroectodermal tumour Ewing's group

Esthesioneuroblastoma (ENB) is a rare, site-specific, locally aggressive ne uronal malignancy so far thought to belong to primitive peripheral neuroect odermal tumour-Ewing's tumour (pPNETs-ETs). Its anatomical location, in add ition to morphologic, immunophenotypic and ultrastructural features, sugges ts its origin in the neuronal or neuroendocrine cells of the olfactory epit helium. However, the cytogenetic and molecular data currently available app ear controversial on the presence of the typical translocation t(11;22)(q24 ;q12) and of trisomy 8, chromosomal changes that characterize the tumours b elonging to the pPNETs-ETs. Herein we have analysed five ENB tumour specime ns for trisomy 8 by fluorescence in situ hybridization (FISH), for the pres ence of EWS gene rearrangements by FISH, reverse transcription polymerase c hain reaction and Southern blot analyses, as well as for the expression of the Ewing sarcoma-associated MIC2 antigen by immunohistochemistry. Neither EWS/FLI-I, EWS/ERG and EWS/FEV fusion genes nor MIC2 expression were found in any tumour, whereas trisomy 8 was found in one case only. Moreover, DNA from three cases analysed by Southern blot did not show EWS gene rearrangem ents. Our results support the evidence that ENB is not a member of the pPNE Ts-ETs. (C) 1999 Cancer Research Campaign.