title: Histological spectrum of oligodendroglial tumors: Only a subset shows 1p/19q codeletion.
abstract: BACKGROUND
  Canonical oligodendroglial tumors (ODGs) are characterized genetically by chromosomes 1p/19q codeletion.
  
  
  OBJECTIVE
  This study was essentially aimed at the detection of frequency of 1p/19q codeletion in the different histological spectrum of ODG tumors in a large cohort of Indian patients.
  
  
  METHODS
  All the ODG tumors evaluated for 1p/19q by fluorescence in-situ hybridization (FISH) during 2009-2015 were correlated with histology, immunohistochemical expression for p53 protein and clinical features.
  
  
  RESULTS
  A total of 676 cases included both pediatric (n = 18) and adult (n = 658) patients. Histologically, 346 pure ODGs [oligodendroglioma (OD) and anaplastic oligodendroglioma (AOD)] and 330 mixed ODGs [oligoastrocytomas (OA), anaplastic oligoastrocytomas (AOA) and glioblastoma with oligodendroglioma component (GBM-O)] were included. 1p/19q co-deletion was noted in 69% (60/87), 55.9% (145/259), 18.2% (18/99), 10.5% (18/172), and in 5.1% (3/59) cases of OD, AOD, OA, AOA, and GBM-O, respectively. In the pediatric age-group, 1p/19q codeletion was seen in 25% (2/8) of pure ODGs and in 10% (1/10) of mixed ODGs. In adults, it was observed in 60% (203/338) cases of pure ODGs and in 11.9% (38/320) cases of mixed ODGs. In adults, pure ODG histology (P = 0.00), frontal location (P = 0.004), calcification [in pure ODGs] (P = 0.03), and lack of p53 protein overexpression (P = 0.00) showed significant statistical correlation with 1p/19q codeletion.
  
  
  CONCLUSIONS
  This study is unique in being one of the largest on ODGs for 1p/19q co-deletion including both pediatric and adult age groups of Indian patients. The results showed co-deletion in 60% of adult ODGs and 25% of pediatric pure ODGs. This reemphasizes the occurrence of 1p/19q codeletion, even though rare, in the pediatric age group.
authors.affiliation: Division of Molecular Pathology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Trupti
authors.initials: T
authors.lastname: Pai
authors.affiliation: Department of Pathology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Epari
authors.affiliation: Division of Molecular Pathology, Tata Memorial Centre, Mumbai, Maharashtra; Department of Pathology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Desai
authors.affiliation: Department of Pathology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Amol
authors.initials: A
authors.lastname: Wadile
authors.affiliation: Department of Radiation Oncology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Tejpal
authors.initials: T
authors.lastname: Gupta
authors.affiliation: Department of Radiation Oncology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Jayant S
authors.initials: JS
authors.lastname: Goda
authors.affiliation: Department of Neurosurgery, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Aliasgar
authors.initials: A
authors.lastname: Moiyadi
authors.affiliation: Department of Neurosurgery, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Prakash
authors.initials: P
authors.lastname: Shetty
authors.affiliation: Department of Pathology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Shubhada
authors.initials: S
authors.lastname: Kane
authors.affiliation: Department of Radiation Oncology, Tata Memorial Centre, Mumbai, Maharashtra, India.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Jalali
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D002648:Child; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics*; D015331:Cohort Studies; D005260:Female; D005909:Glioblastoma / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009837:Oligodendroglioma / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D055815:Young Adult