These rare tumors have both glial and
They usually occur in children and the young,
and present with seizures.
They may mimic a low grade glioma,
Surgery is the primary treatment. The overall
prognosis is favorable.
WHO includes the following in this group:
Ganglioglioma (grade I or II), &
Anaplastic Ganglioglioma (grade III),
Dysplastic gangliocytoma of cerebellum (Lhermitte-Duclos),
Desmoplastic infantile astrocytoma/Ganglioglioma
Dysembryoplastic neuroepithelial tumor (DNT)
Central Neurocytoma (grade III),
Cerebellar Liponeurocytoma (grade I or
Paraganglioma of the filum terminale
is an appropriate
designation, first introduced by Courville in 1930, as it describes
the most frequent form of this rare tumor group which
constitute less than 1% of primary brain tumors. They form 1% of all
intramedullary spinal cord tumors.
The mean age at diagnosis ranges from 16 to
25 years, with highest incidence in children, where they constitute 4% to
10% of primary brain tumors. It has been reported in a 70years old.
Temporal and frontal lobes are the favored
sites. The spinal cord and the brain stem are next commonly involved.
Other less common sites are, optic nerve, chiasma, and tract. An increased
incidence in association with congenital anomalies, such as, agenesis of
corpus callosum and Down's syndrome is noted.
Although metastasis is rare,
leptomeningeal and subarchnoid spread have been reported.
Symptoms are related to the location,
with seizures and focal neurological deficits. Focal neurological
deficits with hydrocephalus occur in midline lesions. It is one of the
common causes of intractable epilepsy.
CT reveals an iso to hypodense
mass, with varying degree and calcifications and cystic changes.
MRI reveals a well circumscribed
mass that is iso to hypodense on T1 and hyperdense on T2 images. There
is variable contrast enhancement.
Grossly, They are firm grayish, avascular
tumor with cystic components.
Histologically, glial and neuronal
elements are present in varying proportions. Glial elements are mostly
In addition to anaplastic
gangliogliomas, other variants include, melanotic astrocytes,
neurocytoma, and pleomorphic xanthoastrocytoma.
Immunohistochemical staining for
synaptophysin, a neuronal cell membrane glycoprotein, helps in
When a ganglion cell
tumor contains populations of small round cells with nuclear
hyperchromasia, it is labelled a ganglioneuroblastoma. These
small cells proliferate rapidly,
Ganglioglioma (H&E): spindle
shaped glial (open arrows) and
ganglion (black arrows) elements.
making the prognosis
worse. This tumor represents an intermediate step on a spectrum from
ganglioglioma to neuroblastoma.
Adenohypophyseal neuronal choristoma
arise from Ganglion
cells within the anterior pituitary gland (hence, it is not a brain
tumor), most often within the substance of a growth hormone producing
pituitary adenoma. Such neural choristomas (or pituicytomas) have been
shown to elaborate growth hormone releasing hormone (GRH).
Surgical resection is the mainstay of
Post operative radiation is reserved for
lesions at eloquent areas, recurrence, and by some for anaplastic
variants. There is no substantial benefit with chemotherapy.
The prognosis is favorable with 10
year survival rate in excess of 90% of cases. Location of the tumor is
found to be a significant factor. Anaplasia, although debatable, does not
alter the prognosis significantly.
Recurrence rate is reported to be about
30%.The recurrence rate, reportedly, is 5 fold and 3.5 fold higher for the
brainstem and the spinal cord, respectively, compared with the risk of
recurrence for cerebral hemispheric tumors.
Desmoplastic Infantile Ganglioglioma (DIGs):
These rare tumors, first described by
Vandenberg et al in 1987. Typically, they are supratentorial and
detected in infants with macrocrania and increased ICT and new onset
seizures. They may reach impressively large sizes and are
characteristically found to have contiguous leptomeningeal involvement, as
reflected by the presence of desmoplasia.
Imaging of these neoplasms typically reveals a large, superficially
located, supratentorial mass with both solid
and cystic components. On CT, the solid component
of a DIG is seen as an avidly enhancing, iso to
hyperdense region that is contiguous with the meninges.
Cystic components underlie solid tumor
On MRI, enhancement
with gadolinium is seen within the solid regions, which
appear hypodense on T1 weighted images, and of variable
density on T2 weighted images. Cystic areas appear
hypodense and hyperdense on T1 and T2weighted
Grossly, it is a firm large avascular mass with leptomenigeal extension.
Histologically, both ganglionic and astrocytic neoplastic elements are
present with dense desmoplasia.
is the primary form of treatment, with post operative radiation, as
advocated by some, in subtotal resections.
generally have favorable prognosis even in subtotal resection.
slowly expanding lesion that produces only local signs. The majority of
patients are under 30 and the temporal lobe is the favored site. It may
be solid or cystic and may show focal calcification.
consists of mature but architecturally abnormal neurons, the glial
component being only sufficient as a stroma.
is a specialized form of gangliocytoma, first reported in 1934.
tumors may largely replace the hypothalamus and usually occur together
with endocrinopathy, e,g, obesity, diabetes insipidus or precocious
children present with precocious puberty before the age of 3 years.
MRI is the imaging of
choice. T1 images show good resolution of the hamartoma from the
surrounding brain with no contrast enhancement.
T2 may show an iso or hyperdense lesion. They may be associated with
midline deformities including callosal agenesis, optic malformations, and
Grossly, the majority are
pedunculated; some are sessile with a wider attachment to the ventral
consist of hypothalamic-type neurons, interspersed with glial cells.
Treatment consists of
hormonal management similar to hormonally active
pituitary tumors and surgery.
A pedunculated tumor is ideal for surgery, by a subtemporal approach.
Radiotherapy has not added to survival.
The outcome is generally
good, even with partial excision.
Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos):
It was first reported in 1920 by Lhermitte
& Duclos. It is am extremely rare posterior fossa hamartomatous
lesion, detected in the 3rd and 4th decades of life, and occasionally in
infancy. Although, usually involving the cerebellar hemipheres, vermian
involvement has been reported.
Familial affliction, and the presence of coexisting congenital anomalies,
such as megalencephaly, heterotopias, and polydactylia, has been
described. An association of has been made between dysplastic
gangliocytoma and Cowden's syndrome, an autosomal dominant disease,
is characterized by the presence of multiple hamartomas.
Clinically they present with signs and symptoms of cerebellar dysfunction,
or increased intracranial pressure secondary to hydrocephalus.
reveals an hypodense, nonenhancing enlargement of cerebellar folia and
coexistent hydrocephalus. There may be calcifications. MRI reveals the
characteristic striated pattern of dysplastic gangliocytoma. These
striations consist of alternating bands of hypo and isodense striations.
Grossly, it is a mass composed of hypertrophied folia with myelination
evident to the eye in the outer part of the molecular layer.
Histologically, there is disruption of
cerebellar architecture with proliferation of ganglion cells in the
granule cell layer. There is thickening of the molecular layer, widening
of the granule cell layer, disappearance of Purkinje cell layer.
Neovascular proliferation may be present in areas with the highest
Surgical resection, and if necessary CSF diversion is the line of
treatment. Some recommend radiation in recurrence.
neuroepithelial tumor - DNT/DNET:
This rare tumor was
described by Daumas-Duport et al in 1988.
uncertain. It is hypothesized to arise from external granular layer of the
The common Locations
are cortical, and temporal lobe, followed by frontal.
They are most common
in children and young adults, but can occur at any age.
is usually with partial complex seizures, especially beginning before age
is based on presence of a specific glioneuronal element, consisting of
oligodendrocytes in a mucinous matrix in which neurons appear to float or
glial nodules associated with cortical dysplasia. Neuronal markers (synaptophysin,
specific enolase) and
glial markers (GFAP, S-100) positive.
CT and MRI reveals
a nodular cortical lesion without edema. They may have megagyric or
multicystic appearance. Occasionally may enhance or contain
calcifications. CT may show calvarial remodeling.
Along with low
grade gliomas, and gangliogliomas they are grouped as a surgically
curable cause of intractable seizures.
behavior, may have high MIB-1 labeling index.
They are usually
stable, even over
long periods, even after subtotal excision. Radiotherapy does not
appear to be of benefit. no data is available on chemotherapy.
These are rare intraventricular tumors that
occur in young adults with a male preponderance. They, probably, represent
a relatively well differentiated form of neuronal tumor. They are
frequently attached to the septum pellucidum or the walls of the lateral
ventricles. Extension through the foramen of monro into the third
ventricle is commonly noted. Extraventricular locations have been
The patients present with features of
hydrocephalus, and seizures in extraventricular ones. Spontaneous
hemorrhage may be the presenting feature in some.
CT and MRI typically reveal a variably
enhancing iso to hyperdense intraventricular mass with calcification and
associated hydrocephalus. Differential diagnosis include oligodendroglioma,
ependymoma, choroid plexus papilloma, subependymoma, and intraventricular
Histologically, they appear as sheets of
uniform cells in a streaming or 'Indian file' arrangement.
Electron microscopy reveals neurosecretory
dense core granules, neuritic processes, and areas resembling synaptic
Immuno histochemistry is often necessary for
diagnosis. Synatophysin and neuron specific enolase reactivity is
Complete excision is the main stay of the
treatment. Role of radiation is debated.
Although thought to be benign, the natural
history is not clear.
Paraganglioma of filum
It is a disease of
adults, unlike other neuronal tumors, and unlike other paragangliomas (Paraganglia,
elsewhere, have been shown to have chemoreceptor roles with modulation of
respiratory and cardiovascular function),
they are non functional. There is male preponderance. They are rare.
Almost always, the location is at L2/3, just distal to conus. They are
slow growing and expand in all directions involving multiple roots at
is like any other degenerative multiple disc degenerative diseases. They
may present with cauda equine syndrome. Diagnosis is usually made after
MRI. It is intradural hyperdense lesion with dural attachment.
Surgery is the
treatment, with careful protection of rootlets. The tumor is very
vascular. Invariably, the tumor is suspended by a feeding artery and its
accompanying vein at the cephalic pole of the tumor. Once this artery is
secured, the tumor becomes avascular. Piecemeal excision is not advised.
Few rootlets need to be sacrificed.
are uniform polygonal cells with pale eosinophilic granular cytoplasm. All
reported intradural cases are benign.
Prognosis is good, with
no recurrence after total excision. Role of radiotherapy, in subtotal
excisions, is not clear.