Last Updated: March 27, 2020
- Malignant, invasive primitive neuroectodermal tumor usually arising within the posterior fossa
- Most common pediatric malignant posterior fossa tumor
- WHO grade IV
- Divided into four molecular subtypes which originate in different locations:
- Wingless (WNT): cerebellar peduncles, CPA cistern
- Sonic hedgehog (SHH): cerebellar hemispheres
- Group 3: 4th ventricle, midline
- Group 4: 4th ventricle, midline
- Divided into four distinct histologic subtypes: classic (most common), desmoplastic, large cell/anaplastic, and extensive nodularity
- Most commonly afflicts children ages 5-12; adult cases rare
- Common presenting signs/symptoms are related to increased intracranial pressure/hydrocephalus
- Headache, nausea, vomiting, altered mental status, papilledema, macrocephaly
- Treatment: surgical resection ± adjuvant chemoradiation
Prognosis varies with molecular subtype and histology:
- Wingless most favorable
- Group 3 least favorable
- Appearance varies with location/subtype
- Solid, rounded 4th ventricular mass most common
- ± 4th ventricular effacement and distortion (in comparison with ependymoma, which often expands/enlarges the 4th ventricle)
- Calcification and cysts occasionally present
- Hemorrhage uncommon
- CSF dissemination common, including drop metastases within the spinal canal (15-50%)
- Fairly homogeneous, mildly hyperdense 4th ventricular mass
- ± hyperdense calcifications or hypodense cysts
- Variable enhancement on contrast-enhanced CT (patchy or homogeneous)
- T1WI: hypointense
- T2WI: iso- to hyperintense
- FLAIR: improved delineation of tumor and CSF; minimal peritumoral edema
- T1WI+C: majority show heterogeneous enhancement, although variable patterns exist; may see CSF dissemination throughout neuraxis
- DWI: demonstrates DWI-bright, ADC-dark diffusion restriction
- MR spectroscopy: elevated Cho, decreased NAA, ± lactate peak
- MRI without and with IV contrast including both brain and spine due to risk of CSF dissemination
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD; Jacob A. Eitel, MD
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Gerber NU, et al. Recent developments and current concepts in medulloblastoma. Cancer Treat Rev. 2014;40:356-365.
Koral K, et al. Imaging characteristics of atypical teratoid-rhabdoid tumor in children compared with medulloblastoma. AJR Am J Roentgenol. 2008;190:809-814.
Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed). Philadelphia, PA: Elsevier, 2016.
Yeom KW, et al. Distinctive MRI features of pediatric medulloblastoma subtypes. AJR Am J Roentgenol. 2013;200:895-903.
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