title: Hyperdiploidy defines a distinct cytogenetic entity of meningiomas.
abstract: BACKGROUND
  The most common chromosomal aberration found in meningiomas is monosomy 22. Progression and recurrence of meningiomas are usually associated with additional chromosome losses. Rarely, however, meningiomas have strongly hyperdiploid karyotypes with over 50 chromosomes; the objective of this study was to explore the cytogenetic and histopathologic patterns as well as the clinical significance of hyperdiploidy in meningiomas.
  
  
  METHODS
  Within a series of 677 consecutive meningiomas, we identified a subgroup comprising 16 cases that display a strikingly uniform pattern of hyperdiploidy mostly without structural chromosome rearrangements, as shown by banding techniques and, in the single structurally aberrant case, spectral karyotyping.
  
  
  RESULTS
  These meningiomas each have between 50 and 56 chromosomes, with trisomy 12 (14/16 cases), trisomy 20 (13/16 cases), trisomy 5 (12/16 cases), and trisomy 17 (10/16 cases). Histomorphologically, hyperdiploid meningiomas feature a heterogeneous phenotype. However, they are associated with a higher histological grade, and decreased expression of alkaline phosphatase as compared to meningiomas with typical karyotype. In two patients, recurrences were documented and three patients died of disease during the period of observation, indicating a worse prognosis of hyperdiploid than of cytogenetically typical meningiomas.
  
  
  CONCLUSIONS
  We conclude that hyperdiploidy constitutes a small but clinically relevant entity of biologically aggressive meningiomas, which are cytogenetically distinguishable from the majority of common-type meningiomas.
authors.affiliation: Neurosurgical Clinic, Saarland University, Homburg/Saar, Germany. ncrket@uniklinik-saarland.de
authors.forename: Ralf
authors.initials: R
authors.lastname: Ketter
authors.forename: Yoo-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Simone
authors.initials: S
authors.lastname: Storck
authors.forename: Jörg
authors.initials: J
authors.lastname: Rahnenführer
authors.forename: Bernd F M
authors.initials: BF
authors.lastname: Romeike
authors.forename: Wolf-Ingo
authors.initials: WI
authors.lastname: Steudel
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Zang
authors.forename: Wolfram
authors.initials: W
authors.lastname: Henn
mesh_terms: D000328:Adult; D000368:Aged; D002877:Chromosomes, Human / Q000235:genetics*; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics; D004171:Diploidy; D018450:Disease Progression; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male; D008577:Meningeal Neoplasms / Q000145:classification / Q000235:genetics* / Q000473:pathology; D008579:Meningioma / Q000145:classification / Q000235:genetics* / Q000473:pathology; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D014314:Trisomy / Q000235:genetics*