Various classification schemata have been used to separate glial tumors into prognostic subsets.[1] According to the most recent classification of the World Health Organization, glial tumors are divided on the basis of histologic criteria into the following subsets: pilocytic astrocytomas, low-grade nonpilocytic astrocytomas, anaplastic gliomas, and glioblastoma multiforme.[2] Various types of nonpilocytic astrocytomas, such as fibrillary protoplasmic and gemistocytic, have been identified. Both malignant and benign varieties of oligodendrogliomas may occur. In young children (especially those younger than 1 year at diagnosis), new variants such as dysembryoplastic neuroepithelial tumor and desmoplastic infantile gangliogliomas are increasingly recognized. Mixed gliomas are classified separately, as are gangliogliomas and other primary neuronal tumors. In general, the grade of the tumor is predictive of outcome; patients with higher-grade tumors have a poorer prognosis. High-grade gliomas with p53 expression and mutation are also associated with a poorer prognosis.[3] MIB-1 labeling index, a marker of cellular proliferative activity, is predictive of outcome in childhood malignant brain tumors. Both histologic classification and proliferative activity evaluation have been shown to be independently associated with survival.[4]

References

1. Burger PC, Sheithauer BW, Vogel FS: Surgical pathology of the nervous system and its coverings. 3rd ed. New York, NY: Churchill Livingstone, 1991. 
   
   
2. Kleihues P, Cavenee WK, eds.: Pathology and Genetics of Tumours of the Nervous System. Lyon, France: International Agency for Research on Cancer, 2000. 
   
   
3. Pollack IF, Finkelstein SD, Woods J, et al.: Expression of p53 and prognosis in children with malignant gliomas. N Engl J Med 346 (6): 420-7, 2002.  [PUBMED Abstract]
   
   
4. Pollack IF, Hamilton RL, Burnham J, et al.: Impact of proliferation index on outcome in childhood malignant gliomas: results in a multi-institutional cohort. Neurosurgery 50 (6): 1238-44; discussion 1244-5, 2002.  [PUBMED Abstract]
   
   

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