Medulloblastoma

Case contributed by Dr Tom Foster

Presentation

Memory issues, headache, ataxia, weakness, past pointing, dysdiadochokinesis and left sided neglect. Bilateral papilledema. ?Intracerebral mass.

Patient Data

Age: 25 years
Gender: Male
CT

5.4 cm mixed solid/cystic mass within the posterior fossa, obstructing the 4th ventricle with resultant hydrocephalus. Descent of tonsils through the foramen magnum.

MRI

Right sided ventricular access device has been placed since the CT scan.

Large left posterior fossa lesion is again seen, mix of solid and cystic components. The cystic components are of high T2/FLAIR signal. The solid components restrict diffusion and demonstrate very mild enhancement.

Case Discussion

Imaging features are consistent with a high grade primary brain tumor. CT of the chest/abdomen/pelvis and MRI spine were also carried out but identified no further findings of significance. 
Differential would include a medulloblastoma or possibly a high grade glioma.

The patient later went on to have the lesion resected and pathology confirmed medulloblastoma:
"Left cerebellar lesion - Classic medulloblastoma WHO Grade 4; SHH activated; no evidence of either MYC or N-MYC amplification"

Medulloblastoma is the most common posterior fossa mass in the pediatric population. It is much less common in adults but should be considered in young adults, especially if imaging features are consistent with medulloblastoma (with the diffusion restriction being a classical finding).

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