Cellular Classification
The classification of brain tumors is based on both histopathologic
characteristics and location in the brain. More than 80% of all childhood
cerebellar gliomas will be pilocytic astrocytomas, which are also considered to
be grade 1 astrocytomas. Most of the remainder will be diffuse or
fibrillary astrocytomas. Malignant gliomas are rare.[1] The pathologic
classification of pediatric brain tumors is a specialized area that is
undergoing evolution; review of the diagnostic tissue by a neuropathologist who
has particular expertise in this area is strongly recommended.
These generally low-grade, often cystic astrocytic tumors are localized to the
cerebellum. Except for malignant gliomas, contiguous spread or metastasis
outside that region is extremely rare. The presence of certain histologic
features has been used retrospectively to stratify cerebellar astrocytomas into
two distinct groups: pilocytic or Gilles type A tumors and diffuse or Gilles
type B tumors; the latter tumors have a poor prognosis.[2] Expert neuropathologic
review is important.
References
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Kleihues P, Cavenee WK, eds.: Pathology and Genetics of Tumours of the Nervous System. Lyon, France: International Agency for Research on Cancer, 2000.
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Gilles FH, Sobel EL, Tavaré CJ, et al.: Age-related changes in diagnoses, histological features, and survival in children with brain tumors: 1930-1979. The Childhood Brain Tumor Consortium. Neurosurgery 37 (6): 1056-68, 1995.
[PUBMED Abstract]
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