Headache, nausea and vomiting and unsteady gait since 1 month.
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- a lobulated rather rounded intraventricular mass lesion is noted filling and expanding the 4th ventricle is seen related to the superior medullary velum (roof of the 4th ventricle), measuring about 4 X 4.5 X 7 cm in its maximal dimensions. The mass elicits heterogenous low T1 with few high signal foci (likely met-Hb signal of subacute blood) and intermediate to high T2 signal with multiple necrotic foci. It shows heterogenous post-contrast enhancement as well as restricted diffusion.
- the mass is compressing the posterior aspect of the brain stem as well as the related cerebellar peduncles and significantly compressing and obstructing the cerebral aqueduct with resultant moderate to marked supra-tentorial hydrocephalic changes as well as mild transependymal CSF permeation seen as mild periventricular T2/FLAIR hyperintensity.
- MRS of the lesion shows depressed N-acetyl apartate (NAA) and creatine (Cr) with incresed choline (Cho) as well as incresed lipid/lactate.
The diagnosis: 4th ventricular mass lesion; consistent with medulloblastoma with moderate supratentorial hydrocephalic changes.
- ependymoma: usually in older children, arises from the floor of the 4th ventricle, more heterogenous with hemorrhage and calcifications. Extension through the lateral foramina of Luschka "plastic tumor".
- cerebellar juvenile pilocytic astrocytoma (JPA): lateral cerebellar cystic mass with enhancing mural nodule.
- choroid plexus papilloma: usually in the 3rd ventricle in children and 4th ventricle in adults. The tumor shows intense and homogeneous enhancement.
- exophytic dorsal pontine glioma: the origin from the dorsal pons with pontine enlargement and filling the 4th ventricle.
- Atypical teratoid/rhabdoid tumor: in young children with almost typical imaging.
- Rasalkar DD, Chu WC, Paunipagar BK, Cheng FW, Li CK.Paediatric intra-axial posterior fossa tumours: pictorial review.Postgrad Med J. 2013 Jan;89(1047):39-46. doi: 10.1136/postgradmedj-2011-130075. Epub 2012 Sep 12. Review. PMID: 22977284 [PubMed - indexed for MEDLINE]