title: Meningeal SWI/SNF related, matrix-associated, actin-dependent regulator of chromatin, subfamily B member 1 (SMARCB1)-deficient tumours: an emerging group of meningeal tumours.
abstract: OBJECTIVE
  Bi-allelic inactivation of SWI/SNF related, matrix-associated, actin-dependent regulator of chromatin, subfamily B member 1 (SMARCB1; also known as INI1) and loss of immunohistochemical expression of SMARCB1 define the group of SMARCB1-deficient tumours. Initially highlighted in malignant rhabdoid tumours, this inactivation has subsequently been observed in several intra and extracranial tumours. To date, primary meningeal SMARCB1-deficient tumours have not been described. We report two cases of meningeal SMARCB1-deficient tumours occurring in adults.
  
  
  METHODS
  We performed immunohistochemical analyses, comparative genomic hybridization, fluorescence in situ hybridization and targeted next-generation sequencing.
  
  
  RESULTS
  The first meningeal tumour was a solitary mass, composed of rhabdoid, adenoid, chordoid and sarcomatoid areas. The second case presented as multiple, bilateral, supra and infratentorial nodules, was composed of fusiform and ovoid cells embedded in a myxoid stroma. Tumour cells were positive for epithelial membrane antigen (EMA), vimentin and CD34 and negative for SMARCB1 and meningothelial, melanocytic, muscular, glial markers. In the first case, one allele of SMARCB1 was completely deleted, whereas in the second case, loss of expression of SMARCB1 was observed as a consequence of a homozygous deletion of SMARCB1.
  
  
  CONCLUSIONS
  The phenotype and genotype of these two cases did not fit diagnostically with entities already known to be SMARCB1-deficient tumours. As both tumours shared common features, they are regarded as belonging to an emerging group of primary meningeal SMARCB1-deficient tumours, not described to date. To facilitate the identification and characterization of these tumours, we recommend SMARCB1 immunohistochemistry for primary meningeal tumours which are difficult to classify, especially if immunopositive for EMA and CD34.
authors.affiliation: Central Laboratory of Pathology of Nice University Hospital, France.|Laboratory of Solid Tumors Genetics, Nice University Hospital, France.
authors.forename: B
authors.initials: B
authors.lastname: Dadone
authors.affiliation: Department of Neurosurgery, Nice University Hospital, France.
authors.forename: D
authors.initials: D
authors.lastname: Fontaine
authors.affiliation: Department of Radiology, Nice University Hospital, France.
authors.forename: L
authors.initials: L
authors.lastname: Mondot
authors.affiliation: Institute for Research on Cancer and Aging of Nice (IRCAN), CNRS UMR 7284/INSERM U1081, University of Nice Sophia-Antipolis, Nice, France.
authors.forename: G
authors.initials: G
authors.lastname: Cristofari
authors.affiliation: Department of Pathology and Neuropathology, Groupement Hospitalier Est, Lyon Bron, France.
authors.forename: A
authors.initials: A
authors.lastname: Jouvet
authors.affiliation: Department of Pathology, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: C
authors.initials: C
authors.lastname: Godfraind
authors.affiliation: Department of Neuropathology, Sainte-Anne Hospital, Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Varlet
authors.affiliation: Department of Biopathology, Centre Léon Bérard, Lyon, France.
authors.forename: D
authors.initials: D
authors.lastname: Ranchère-Vince
authors.affiliation: Department of Pathology, Institut Bergonié, Bordeaux, France.
authors.forename: J-M
authors.initials: JM
authors.lastname: Coindre
authors.affiliation: Department of Oncology, Centre Antoine Lacassagne, Nice, France.
authors.forename: L
authors.initials: L
authors.lastname: Gastaud
authors.affiliation: Institute for Research on Cancer and Aging of Nice (IRCAN), CNRS UMR 7284/INSERM U1081, University of Nice Sophia-Antipolis, Nice, France.
authors.forename: C
authors.initials: C
authors.lastname: Baudoin
authors.affiliation: Laboratory of Solid Tumors Genetics, Nice University Hospital, France.|Institute for Research on Cancer and Aging of Nice (IRCAN), CNRS UMR 7284/INSERM U1081, University of Nice Sophia-Antipolis, Nice, France.
authors.forename: A-C
authors.initials: AC
authors.lastname: Peyron
authors.affiliation: Department of Oncology, Centre Antoine Lacassagne, Nice, France.
authors.forename: A
authors.initials: A
authors.lastname: Thyss
authors.affiliation: Department of Pathology, West Kent Cancer Centre, Maidstone, UK.
authors.forename: M
authors.initials: M
authors.lastname: Coutts
authors.affiliation: Central Laboratory of Pathology of Nice University Hospital, France.
authors.forename: J-F
authors.initials: JF
authors.lastname: Michiels
authors.affiliation: Laboratory of Solid Tumors Genetics, Nice University Hospital, France.|Institute for Research on Cancer and Aging of Nice (IRCAN), CNRS UMR 7284/INSERM U1081, University of Nice Sophia-Antipolis, Nice, France.
authors.forename: F
authors.initials: F
authors.lastname: Pedeutour
authors.affiliation: Central Laboratory of Pathology of Nice University Hospital, France.
authors.forename: F
authors.initials: F
authors.lastname: Burel-Vandenbos
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000235:genetics* / Q000473:pathology*; D000071796:SMARCB1 Protein / Q000235:genetics*
chemical_list: D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human
keywords: INI1; SMARCB1; SWI/SNF related, matrix-associated, actin-dependent regulator of chromatin, subfamily B member 1; meningeal tumour; meninges