Pilocytic astrocytoma arising from an area of nudular heterotopia located in the white matter of the temporal lobe: case report

A 16-year-old girl suffering from intractable temporal lobe epilepsy presented with a pilocytic astrocytoma, which occurred in an area of nodular heterotopia located in the white matter of the temporal lobe. The pilocytic astrocytoma appeared to be covered by an area of gliosis, which contained numerous Rosenthal fibers, while in the lesion the pilocytic astrocytoma occupied a small area. The gliosis eventually became a tumor-like lesion. The while matter around the mass was composed of gliosis with nodular heterotopia. Temporal developmental malformation, which was a basic lesion of the patient, might therefore be a precursor lesion of pilocytic astrocytomas.