The significance of this classification system is that it attempts, by consensus, to synchronize the organization and description of human neoplasms between countries and continents. The 1993 revision represents a significant change and improvement from the original 1979 formulation. Anne s system should take comfort in the new WHO scheme because of many shared similarities. Low grade astrocytomas are now clearly divided into specific tumor subtypes, recognizing the unique favorable prognosis associated with juvenile pilocytic astrocytoma, subependymal giant cell astrocytoma, and several other variants. Vascular changes are usually limited to capillary proliferations that may include glomeruloid capillaries and endothelial proliferation.
Calcification is possible.
Usually seen with other features of Tuberous Sclerosis. May obstruct f. of Monro and cause hydrocephalus. Enhancement and calcification are both common. Usually a large hemispheric mass, closely related to the cerebral surface. May have a disturbingly heterogeneous appearance with cyst formation, variable calcification, and prominent enhancement.