Vignette: kid with seizures + bubbly lesion in temporal lobe
intracortical nodular-appearing neoplasm (features similar to cortical dysplasia) enlarging gyrus (forming megagyrus).
2/3 (62%) in temporal cortex, 1/3 (31%) in frontal cortex.
cystic changes, frequent association with dysplastic cortex.
hypocellular lesion - well-differentiated normal neurons "floating" in pool of mucopolysaccharide-rich fluid (stains with alcein blue) and surrounded (but NOT tightly*) by neoplastic oligodendroglial-like cells without anaplastic features.
*main difference from oligodendroglioma (perineural satellitosis)
Note absence of perineuronal satellitosis (i.e. neurons are NOT tightly surrounded by other cells), which is typically seen in oligodendroglial tumors;
Perivascular and perineuronal satellitosis is characteristic of oligodendroglioma spread into grey matter:
- often presents as intractable partial seizures.
no neurological deficits (or stable congenital deficit).
MRI - variable signal and enhancement characteristics (≈ low-grade astrocytoma).
T2-MRI - right-sided temporal abnormality (arrow) with thickened cortex, poorly demarcated from white matter:
T1-MRI - well-circumscribed neoplasm originating in cortical region (arrows); inner table of skull has been remodeled (suggesting slow-growing neoplasm):
- good prognosis after surgical extirpation.
rare postoperative complication - schizophreniform psychosis, paranoia, and depression.
radiation and chemotherapy have no clear benefit.
- rare benign slowly growing CNS tumors:
Ganglioglioma (95%) - contains both astrocytic and neuronal components; glial component is most commonly astrocytic, but it may be oligodendroglial.
gangliocytoma (5%) - only neuronal component without glial component.
MRI – nonspecific.
MR spectroscopy – choline-to-creatine ratio is lower and N-acetyl aspartate-to-creatine ratio* is higher than in gliomas.
*N-acetyl aspartate↑ is due to neuronal component
Solid enhancing tumor in temporal lobe with no surrounding edema in younger patient with intractable seizures
Partly cystic ganglioglioma in left temporal lobe with abnormal signal (arrow), without contrast enhancement:
A) Axial T1 with gadolinium.
B) Axial FLAIR.
C) Axial T2.
D) Coronal T2.
Gadolinium-enhanced T1-MRI - enhancing tumor involving hippocampus, uncus, and amygdala:
Exophytic temporal lobe ganglioglioma (T1-MRI with contrast) - large mass originating from medial aspect of left temporal lobe; both solid and cystic components; large exophytic component extends through tentorial incisura into superior cerebellar cistern; tumor has also compressed atrium of left lateral ventricle:
complete resection is generally curative (radiation is rarely indicated); may have good prognosis even when untreated (but incomplete removals are associated with local recurrence).
use of chemotherapy has not been reported.
poor prognosis factors – age < 1 yr, brainstem involvement.
Lhermitte-Duclos disease (s. dysplastic gangliocytoma of cerebellum)