title: Immunohistochemical classification of primary and secondary glioblastomas.
abstract: BACKGROUND
  Glioblastomas may develop de novo (primary glioblastomas, P-GBLs) or through progression from lower-grade astrocytomas (secondary glioblastomas, S-GBLs). The aim of this study was to compare the immunohistochemical classification of glioblastomas with clinically determined P-GBLs and S-GBLs to identify the best combination of antibodies for immunohistochemical classification.
  
  
  METHODS
  We evaluated the immunohistochemical expression of epidermal growth factor receptor (EGFR), p53, and isocitrate dehydrogenase 1 (IDH-1) in 150 glioblastoma cases.
  
  
  RESULTS
  According to clinical history, the glioblastomas analyzed in this study consisted of 146 P-GBLs and 4 S-GBLs. Immunohistochemical expression of EGFR, p53, and IDH-1 was observed in 62.6%, 49.3%, and 11.1%, respectively. Immunohistochemical profiles of EGFR(+)/p53(-), IDH-1(-)/EGFR(+)/p53(-), and EGFR(-)/p53(+) were noted in 41.3%, 40.2%, and 28.7%, respectively. Expression of IDH-1 and EGFR(-)/p53(+) was positively correlated with young age. The typical immunohistochemical features of S-GBLs comprised IDH-1(+)/EGFR(-)/p53(+), and were noted in 3.6% of clinically P-GBLs. The combination of IDH-1(-) or EGFR(+) was the best set of immunohistochemical stains for identifying P-GBLs, whereas the combination of IDH-1(+) and EGFR(-) was best for identifying S-GBLs.
  
  
  CONCLUSIONS
  We recommend a combination of IDH-1 and EGFR for immunohistochemical classification of glioblastomas. We expect our results to be useful for determining treatment strategies for glioblastoma patients.
authors.affiliation: Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyu Sang
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Department of Pathology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: Gheeyoung
authors.initials: G
authors.lastname: Choe
authors.affiliation: Department of Pathology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: Kyung Han
authors.initials: KH
authors.lastname: Nam
authors.affiliation: Department of Pathology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: An Na
authors.initials: AN
authors.lastname: Seo
authors.affiliation: Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Sumi
authors.initials: S
authors.lastname: Yun
authors.affiliation: Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyung Ju
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hwa Jin
authors.initials: HJ
authors.lastname: Cho
authors.affiliation: Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Sung Hye
authors.initials: SH
authors.lastname: Park
keywords: Genes, erbB-1; Genes, p53; Glioblastoma; IDH1 protein, human; Immunohistochemistry