Sellar Region Atypical Teratoid/Rhabdoid Tumors (ATRT) in Adults Display DNA Methylation Profiles of the ATRT-MYC Subgroup

Am J Surg Pathol. 2018 Apr;42(4):506-511. doi: 10.1097/PAS.0000000000001023.

Abstract

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant brain tumor predominantly encountered in infants. Mutations of the SMARCB1 gene are the characteristic genetic lesion. A small group of ATRT stands out clinically, because these tumors are located in the sellar region of adults. To investigate if sellar region ATRT in adults represents a molecular distinct entity, we characterized molecular alterations in 7 sellar region ATRTs in adults as compared with 150 pediatric ATRTs and 47 pituitary adenomas using SMARCB1 sequencing, multiplex ligation-dependent probe amplification and fluorescence in situ hybridization as well as DNA methylation profiling. The median age of the 6 female and 1 male patients was 56 years. On histopathologic examination, all tumors were malignant rhabdoid tumors showing loss of SMARCB1/INI1 protein expression. Two cases displayed compound heterozygous SMARCB1 point mutations, 3 cases showed heterozygous SMARCB1 deletions with point mutations of the other allele and 1 case a homozygous SMARCB1 deletion; in 1 case, underlying SMARCB1 alterations could not be identified. On unsupervised hierarchical cluster analysis of DNA methylation profiles, sellar region ATRTs did not form a distinct group, but clustered with ATRT-MYC, 1 of 3 recently described molecular subgroups of ATRT. On analysis of DNA methylation array intensity data, only 1 sellar region ATRT showed characteristic features of pediatric ATRT-MYC, that is, major copy number losses affecting the SMARCB1 region. In conclusion, these results suggest that sellar region ATRTs in adults form a clinically distinct entity with a different mutational spectrum, but epigenetic similarities with pediatric ATRTs of the ATRT-MYC subgroup.

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Biomarkers, Tumor / genetics*
  • DNA Methylation*
  • Epigenesis, Genetic*
  • Female
  • Gene Deletion
  • Genetic Predisposition to Disease
  • Humans
  • Male
  • Middle Aged
  • Phenotype
  • Pituitary Neoplasms / genetics*
  • Pituitary Neoplasms / pathology
  • Point Mutation
  • Rhabdoid Tumor / genetics*
  • Rhabdoid Tumor / pathology
  • SMARCB1 Protein / genetics*
  • Teratoma / genetics*
  • Teratoma / pathology
  • Young Adult

Substances

  • Biomarkers, Tumor
  • SMARCB1 Protein
  • SMARCB1 protein, human

Supplementary concepts

  • Teratoid Tumor, Atypical