Gangliogliomas usually present with a subacute to chronic clinical course owing to their very slow growth. As with other primary tumors, their border with surrounding CNS is indistinct. Features such as perivascular lymphocytic infiltrates, cyst formation and calcification are typical. The key components of these tumors are a highly variable mixture of glia and neurons. The glial component is most often astrocytic but may be predominantly oligodendrocytic or mixed and may show variable anaplasia.
Mitotic activity is unusual.
The neurons of gangliogliomas are notable for several typical architectural features. They are individually randomly oriented in a fibrillary matrix. Their size and shape are highly variable with frequent multinucleation and large bizarre forms. Finally, the neuronal component is often irregularly clustered and may be lobulated by bundles of reticulin. Immunohistochemistry demonstrates neuronal expression of NSE, NF, SYN, microtubule associated proteins, class III beta tubulin and chromogranin.