Weekly Image Challenge – October 2, 2022

What is the most likely diagnosis in the scans of a 3 years old boy?

  1. Ependymoma
  2. Medulloblastoma
  3. Choroid plexus carcinoma
  4. Dermoid cyst
  5. Astrocytoma


 Congratulations to all those who guessed Ependymoma. Ependymoma is most commonly located in the 4th ventricle arising from the floor. It is a heterogenous mass, with vivid contrast enhancement. There is no surrounding edema. The mass tumor effect also displaces the brainstem, and the tumor can be seen extending to the foramina of Lushka and Megendie, unlike Medulloblastoma.

Medulloblastoma arises from the roof of the 4th ventricle, shows contrast enhancement, and is a close differential diagnosis for this case.

Choroid plexus carcinoma is usually located in the trigone of lateral ventricle, has more homogenous contrast enhancement, and can invade the brain parenchyma.

The dermoid cyst does not show contrast enhancement.

Astrocytoma is located in the brain parenchyma and usually effaces the ventricle rather than extending into it. It may or may not show contrast enhancement depending on the tumor grade.