title: [Solitary fibrous tumors and hemangiopericytomas of the meninges: Immunophenotype and histoprognosis in a series of 17 cases].
abstract: BACKGROUND
  The 2007 World Health Organization (WHO) classification of tumors of the central nervous system distinguishes meningeal hemangiopericytomas (HPC) from solitary fibrous tumors (TFS). In the WHO classification of tumors of soft tissue and bone, those neoplasms are no longer separate entities since the discovery in 2013 of a common oncogenic event, i.e. the NAB2-STAT6 gene fusion. A shared histopronostic grading system, called "Marseille grading system", was recently proposed, based on hypercellularity, mitotic count and necrosis. We evaluated the immunophenotype and histoprognosis in a retrospective cohort of intracranial HPC and TFS.
  
  
  METHODS
  Fifteen initial tumors and 2 recurrences were evaluated by immunohistochemistry for STAT6, CD34, EMA, progesterone receptors and Ki67. The pronostic value of the WHO and the Marseille grading systems was tested on 12 patients with clinical follow-up.
  
  
  RESULTS
  Initial tumors were 11 HPC and 4 SFT. STAT6 and CD34 were expressed in 16/17 tumors, EMA and progesterone receptors in 2 and 5 cases, respectively. The Ki67 labelling index was 6.25% in HPC and 3% in SFT. Half of the tumors recurred between 2 years and 9 years after initial diagnosis (mean time 5 years). No statistical difference in the risk of recurrence was associated with either grade (WHO or Marseille), in this small cohort.
  
  
  CONCLUSIONS
  The diagnosis of HPC and TFS is facilitated by the almost constant immuno-expression of STAT6, and this justifies their common classification. The high rate of recurrence implies a very long-term follow-up because the current grading systems do not accurately predict the individual risk.
authors.affiliation: Département de pathologie cellulaire et tissulaire, CHU d'Angers, 4, rue Larrey, 49933 Angers, France. Electronic address: caro-savary@hotmail.com.
authors.forename: Caroline
authors.initials: C
authors.lastname: Savary
authors.affiliation: Département de pathologie cellulaire et tissulaire, CHU d'Angers, 4, rue Larrey, 49933 Angers, France. Electronic address: mcrousselet@chu-angers.fr.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Rousselet
authors.affiliation: Département de pathologie cellulaire et tissulaire, CHU d'Angers, 4, rue Larrey, 49933 Angers, France. Electronic address: somichalak-provost@chu-angers.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Michalak
authors.affiliation: Service de neurochirurgie, CHU d'Angers, 4, rue Larrey, 49933 Angers, France. Electronic address: hdfournier@chu-angers.fr.
authors.forename: Henri-Dominique
authors.initials: HD
authors.lastname: Fournier
authors.affiliation: Service d'anatomie et cytologie pathologiques, CHU de Poitiers, 2, rue de la Milétrie, 86021 Poitiers, France. Electronic address: michael.taris@gmail.com.
authors.forename: Michaël
authors.initials: M
authors.lastname: Taris
authors.affiliation: Service d'anatomie et cytologie pathologiques, CHU de Nantes, boulevard Professeur-Jacques-Monod, 44800 Saint-Herblain, France. Electronic address: delphine.loussouarn@chu-nantes.fr.
authors.forename: Delphine
authors.initials: D
authors.lastname: Loussouarn
authors.affiliation: Département de pathologie cellulaire et tissulaire, CHU d'Angers, 4, rue Larrey, 49933 Angers, France. Electronic address: aurousseau@chu-angers.fr.
authors.forename: Audrey
authors.initials: A
authors.lastname: Rousseau
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D005260:Female; D005500:Follow-Up Studies; D006393:Hemangiopericytoma / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D006801:Humans; D016130:Immunophenotyping; D008297:Male; D008577:Meningeal Neoplasms / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D008875:Middle Aged; D060787:Neoplasm Grading; D009363:Neoplasm Proteins / Q000032:analysis; D009364:Neoplasm Recurrence, Local / Q000737:chemistry / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D054364:Solitary Fibrous Tumors / Q000737:chemistry / Q000145:classification / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins
keywords: Grade histopronostique; Grading; Hemangiopericytoma; Histoprognosis; Hémangiopéricytome; Meninges; Méninges; STAT6; Solitary fibrous tumor; Tumeur fibreuse solitaire