title: Polyploidy in atypical grade II choroid plexus papilloma of the posterior fossa.
abstract: Cytogenetic studies of choroid plexus tumors, particularly for atypical choroid plexus papillomas, have been rarely described. In the present report, the cytogenetic investigation of an atypical choroid plexus papilloma occurring at the posterior fossa of a 16-year-old male is described. Comparative genome hybridization analysis demonstrated gains of genetic material from almost all chromosomes. Chromosome losses involved 19p, regional losses at chromosome X and loss of chromosome Y. The presence of polyploid cells was confirmed by fluorescence in situ hybridization analysis with probes directed to centromeric regions. Furthermore, the microscopic analysis of cultures showed nuclear buds, nucleoplasmic bridges, and micronuclei in 23% of tumor cells suggesting the presence of complex chromosomal abnormalities. Previous cytogenetic studies on choroid plexus papillomas showed either normal, hypodiploid or hyperdiploid karyotypes. To the best of our knowledge, this is the first report of polyploidy in choroid plexus papilloma of intermediate malignancy grade. Although the mechanisms beneath such genome duplication remain to be elucidated, the observed abnormal nuclear shapes indicate constant restructuring of the tumor's genome and deserves further investigation.
authors.affiliation: Division of Pediatric Oncology, Department of Pediatrics, University of São Paulo, Av. Bandeirantes 3900, São Paulo, Brazil. marsol@rge.fmrp.usp.br
authors.forename: María Sol
authors.initials: MS
authors.lastname: Brassesco
authors.forename: Elvis Terci
authors.initials: ET
authors.lastname: Valera
authors.forename: Luciano
authors.initials: L
authors.lastname: Neder
authors.forename: Angel Mauricio
authors.initials: AM
authors.lastname: Castro-Gamero
authors.forename: Darlene
authors.initials: D
authors.lastname: Arruda
authors.forename: Hélio Rubens
authors.initials: HR
authors.lastname: Machado
authors.forename: Elza Tiemi
authors.initials: ET
authors.lastname: Sakamoto-Hojo
authors.forename: Luiz Gonzaga
authors.initials: LG
authors.lastname: Tone
mesh_terms: D000293:Adolescent; D002467:Cell Nucleus / Q000235:genetics / Q000473:pathology; D053144:Cell Nucleus Shape; D002503:Centromere / Q000473:pathology; D002869:Chromosome Aberrations; D055028:Comparative Genomic Hybridization; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D015192:Infratentorial Neoplasms / Q000235:genetics* / Q000473:pathology; D008297:Male; D009367:Neoplasm Staging; D020288:Papilloma, Choroid Plexus / Q000235:genetics* / Q000473:pathology; D011123:Polyploidy