title: Phenotypical and molecular distinctness of sinonasal haemangiopericytoma compared to solitary fibrous tumour of the sinonasal tract.
abstract: OBJECTIVE
  Sinonasal haemangiopericytoma (SN-HPC) is a rare sinonasal mesenchymal neoplasm of perivascular myoid cell origin. Solitary fibrous tumour (SFT) occurs only very rarely in the sinonasal tract. SFT and soft tissue HPC have been considered a single entity. Recently, recurrent gene fusions involving NAB2-STAT6 resulting in differential expression of STAT6 were characterized as central molecular events in SFT. However, no data exist for NAB2-STAT6 status or STAT6 expression in SN-HPC.
  
  
  RESULTS
  We examined six SN-HPCs and two sinonasal SFTs by immunohistochemistry and RT-PCR for NAB2-STAT6 fusions. SN-HPC affected three females and three males (mean age: 72 years). They expressed smooth muscle actin, lacked strong CD34 reactivity and were negative for nuclear STAT6 expression. RT-PCR analysis confirmed the absence of NAB2-STAT6 fusions in all cases. Conversely, both sinonasal SFTs (in males aged 39 and 52 years) displayed classical features of pleuropulmonary and soft-tissue SFTs (uniformly CD34-positive with strong nuclear expression of STAT6). RT-PCR revealed NAB2-STAT6 fusions in both cases.
  
  
  CONCLUSIONS
  These findings confirm the molecular and phenotypical distinctness of these two entities. While SN-HPC is a site-specific sinonasal neoplasm of as yet unknown molecular pathogenesis, sinonasal SFTs show phenotypical and molecular identity to their pleural/extrapleural counterparts.
authors.affiliation: Institute of Pathology, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Abbas
authors.initials: A
authors.lastname: Agaimy
authors.forename: Sarah
authors.initials: S
authors.lastname: Barthelmeß
authors.forename: Helene
authors.initials: H
authors.lastname: Geddert
authors.forename: Carsten
authors.initials: C
authors.lastname: Boltze
authors.forename: Evgeny A
authors.initials: EA
authors.lastname: Moskalev
authors.forename: Michael
authors.initials: M
authors.lastname: Koch
authors.forename: Stefan
authors.initials: S
authors.lastname: Wiemann
authors.forename: Arndt
authors.initials: A
authors.lastname: Hartmann
authors.forename: Florian
authors.initials: F
authors.lastname: Haller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D005260:Female; D050939:Gene Fusion; D006393:Hemangiopericytoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009669:Nose Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D009928:Organ Specificity; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D050800:STAT6 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D054364:Solitary Fibrous Tumors / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; C491000:NAB2 protein, human; D012097:Repressor Proteins; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human
keywords: NAB2; STAT6; gene fusion; head and neck; sinonasal haemangiopericytoma; solitary fibrous tumour