title: Rapid malignant transformation of low-grade astrocytomas: report of 2 cases and review of the literature.
abstract: BACKGROUND
  Low-grade gliomas have been documented to undergo transformation into high-grade astrocytomas, and the time interval of this transformation has been reported to generally occur within 5 years in about 50% of patients harboring these low-grade lesions. Several studies have investigated the evolution of low-grade gliomas into malignant gliomas by CT and MRI characteristics, but many have not documented the timing of these transformation processes.
  
  
  METHODS
  The authors discuss the cases of 2 patients with histopathologically confirmed grade II astrocytomas after craniotomies that underwent rapid evolution into malignant gliomas within 13 weeks. Interestingly, both low-grade astrocytomas were positive with immunostaining for the epidermal growth factor receptor, in which its amplification has been implicated as a molecular marker of malignant gliomas. In addition, the grade II astrocytomas were negative for p53 in both patients but were found to be positive upon transformation into malignant gliomas.
  
  
  CONCLUSIONS
  To our knowledge, this is the first report of rapid malignant transformation of low-grade gliomas, which were proven by histology, within 13 weeks. There may be patients with a subtype of low-grade astrocytomas that may warrant molecular characterization to determine if aggressive adjuvant therapy would be of benefit.
authors.affiliation: Department of Neurosurgery, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Frazier
authors.forename: Michael W
authors.initials: MW
authors.lastname: Johnson
authors.forename: Peter C
authors.initials: PC
authors.lastname: Burger
authors.forename: Jon D
authors.initials: JD
authors.lastname: Weingart
authors.forename: Alfredo
authors.initials: A
authors.lastname: Quinones-Hinojosa
mesh_terms: D001254:Astrocytoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D002471:Cell Transformation, Neoplastic; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D016159:Tumor Suppressor Protein p53; D066246:ErbB Receptors