Medulloblastoma with leptomeningeal seeding

Case contributed by Saeed Soltany Hosn
Diagnosis certain


6-year-old female presented with projectile vomiting and headache of two weeks duration. Initially she is evaluated as a case of sepsis.

Patient Data

Age: 6 Y/o
Gender: Female

Non contrast CT scan obtained immediately after admission shows a hyperdense mass lesion with central calcification in the inferior vermis with associated marked hydrocephalus.

The MRI shows a heterogeneous lobulated mass lesion arising from the cerebellar vermis which causes tetra-ventricular  hydrocephalus. Notice the stretching of the corpus callosum. The mass is primarily hypointense on T1WI and relatively hyperintense on long TR images with diffuse intense contrast enhancement. There is also evidence of extension through the foramen of luschka into the right medullary and cerebellopontine angle cisterns. In addition, a diffuse and relatively thick leptomeningeal enhancement is observed in the bilateral sylvian fissures, ambient , suprasellar and in the quadrigeminal cisterns. 


Annotated image

There is thickening and enhancements of the left trigeminal nerve (arrow)

Case Discussion

She underwent craniotomy and histopathology confirmed medulloblastoma. Sometimes, as in this case, the MRI features of 4th ventricle ependymoma  and medulloblastoma overlaps and differentiation can be difficult based only on imaging; however, on non contrast CT scan meduloblastoma can be distinguished from ependymoma by its higher attenuation. Calcification can be seen in both but is more common in ependymoma. Also extension of the tumor through the foramina of Luschka and Magendie is characteristic for plastic ependymoma and is considered unusual for medulloblastoma.

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