Fact-sheet: Atypical teratoid rhabdoid tumor of the brain
Updated on 10/03/2018 at 2:40 PM
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Definition
Atypical teratoid/rhabdoid tumors (AT/RT) of the central nervous system are rare, aggressive malignant tumors, classified as WHO grade IV.
These tumors are highly heterogeneous both morphologically and immunophenotypically.
They occur in early childhood (before the age of 5).
The diagnosis should be considered in any large, aggressive brain tumor in a child under 3 years of age.
Most often, they are located in the posterior fossa, in the vermis or cerebellar hemispheres (50% of cases).
Otherwise, they have a supratentorial location, or even a combined infra- and supratentorial location.
Ependymal or leptomeningeal dissemination is possible.
Clinical features
Look for:
- signs of intracranial hypertension: increased head circumference, lethargy, vomiting.
- torticollis, seizures, psychomotor regression, behavioral disturbances.
CT
Brain CT most often shows a large mass at the time of diagnosis.
It is spontaneously hyperdense on unenhanced CT.
Calcifications are sometimes found.
Enhancement after contrast injection is intense and heterogeneous.
MRI
Brain MRI shows a heterogeneous mass with diffusion hyperintensity (ADC restriction) (hypercellular tumor).
- On T1-weighted sequences: isointense to the brain parenchyma. Intratumoral hemorrhagic foci may be present, appearing hyperintense on T1, or cysts hyperintense to CSF.
- On T2: heterogeneous. Hypointense (hemorrhagic) or hyperintense (cystic) foci.
- On T2 FLAIR: little perilesional edema relative to tumor size. Solid tumor iso- to hyperintense. Cysts hyperintense to CSF.
- On T2*: hypointense hemorrhagic foci.
- Contrast enhancement is intense, heterogeneous, always present.
Other leptomeningeal and spinal cord locations should be sought.
Management
Treatment: surgery, radiochemotherapy.
Differential diagnosis
Other posterior fossa tumors:
- Medulloblastoma
- Ependymoma
- Choroid plexus papilloma
- Glioblastoma / sarcoma
- Teratoma