CHILDHOOD BRAIN TUMORSNabilah binti Dato’ Ayob

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Astrocytoma

Astrocytoma is the most common brain tumor, accounting for more than half of all primary CNS malignancies.(Peads)

Originate in glial-cells: called astrocytes. Astrocytomas come in four major subtypes:

Juvenile pilocytic astrocytoma (grade 1) Fibrillary/diffuse astrocytoma (grade 2) Anaplastic astrocytoma (grade 3) Glioblastoma multiforme (grade 4)

Most cases occur in the first decade of life Peak age at 5-9 years.

Astrocytoma

Pilocytic astrocytomas arise throughout the neuraxis, but preferred sites optic nerve, optic chiasm / hypothalamus, thalamus and basal ganglia, cerebral hemispheres, cerebellum, and brain stem.

Diffuse astrocytomas may arise in any area of the CNS but most commonly cerebrum, particularly the frontal and temporal lobes.

Anaplastic astrocytoma arises in the same locations as diffuse astrocytomas, with a preference for the cerebral hemispheres increased cellularity, marked mitotic activity, and a tendency to infiltrate through neighboring tissue.

Astrocytoma

Glioblastoma multiforme subcortical white matter of the cerebral hemispheres. Combined frontotemporal location with infiltration into the adjacent cortex, basal ganglia, and contralateral hemisphere is typical.

Glioblastoma most frequent brain stem in children. These tumors are highly cellular, with high proliferative and mitotic activity.

Juvenile pilocytic astrocytoma of the cerebellum (MRI).

Supratentorial glioblastoma multiforme(MRI)

T2-weighted image of a diffuse intrinsic pontine glioma.

Grade 2 diffuse astrocytoma

Medulloblastoma

Medulloblastoma is the most common malignant brain tumor in children, accounting for 10-20% of primary CNS neoplasms and approximately 40% of all posterior fossa tumors Highly invasive embryonal neuroepithelial tumor

Cerebellar tumor arising predominantly from the cerebellar vermis

Morphologically similar tumors arising in the pineal region are termed pineoblastomas, and those arising in other CNS locations are called primitive neuroectodermal tumors (PNETs)

Medulloblastoma

The tumor may spread contiguously, to the cerebellar peduncle and/or the floor of the fourth ventricle

anteriorly, to the brainstem

Inferiorly, to the cervical spine

Superiorly, above the tentorium.

It also may spread via the CSF intracranially or to the leptomeninges and spinal cord.

MRI showing a medulloblastoma of the cerebellum.

A cross-section of medulloblastoma (PNET) sitting in the cerebellum

Ependymoma Ependymoma neoplasm composed of glial cells

that have differentiated along ependymal lines. Most common Ependymal lining of the ventricles

(most often the floor, roof, or lateral recesses of the fourth ventricle) but it also arises in the filum terminale and the central spinal canal.

3rd most common brain tumor in children, accounting for approximately 10% of primary CNS neoplasms

 Tends to invade locally, even if histological appearance is benign.

Approximately 90% of tumors are intracranial, with as many as 70% occurring in the posterior fossa.

Ependymoma of the 4th ventricle (CT-contrast)

- Ventricular enlargement

Anaplastic ependymoma of the lateral ventricle in an 8-week-old girl with hydrocephalus

Craniopharyngioma

Craniopharyngiomas histologically benign neuroepithelial tumors that are predominately observed in children aged 5-10 years.

These tumors arise from squamous cell embryologic rests found along the path of the primitive adenohypophysis and craniopharyngeal duct.

Pediatric craniopharyngiomas are believed to arise from cellular remnants of the Rathke pouch, which is an embryologic structure that forms both the infundibulum and anterior lobe of the pituitary gland.

a) Note that the lesion is sharply demarcated and smoothly contoured. This fluid-filled mass is consistent with a typical craniopharyngioma.

b) Image demonstrates a cystic lesion in the typical location of a craniopharyngioma.

Choroid plexus papillomas Choroid plexus papillomas may arise wherever

a choroid plexus exists. In all age groups, the sites at which choroid plexus papillomas occur, in order of frequency, are the lateral ventricles (43%), fourth ventricle (39%), third ventricle (10%), and cerebellopontine angle (8%).

Of all choroid plexus papillomas, 20% occur in patients younger than 1 year old, and 85% occur in those younger than 10 years old.

On gross pathologic examination, choroid plexus papillomas appear as lobulated, encapsulated masses.

Demonstrates enhancing lateral ventricular mass(CT).

Shows intense heterogeneous enhancement extension into the third ventricle.

A germ cell tumor/Germinoma Arises from primitive developing cells

that form in the embryo and may otherwise become the reproductive system.

Most commonly found in the pineal and suprasellar regions.

Approximately 2 percent of all pediatric brain tumors. Half of it occur in young people (10-20 y.o)

Mass in the epiphysial area These are typical localisations, the lesions crawl

along the floor of the 3rd ventricle.