Neuroradiology Board Review – Brain Tumors – Case 18

Neuroradiology brain tumor board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case starts with 2 axial images from a CT through the posterior fossa followed by MRI images through the same region. There is a heterogeneous lesion to the left of the midline along the left foramen of Lushka. On postcontrast images, it is pretty avidly enhancing. The enhancing margins are pretty well defined and it looks like it is wholly in the ventricle.

The diagnosis is: ependymoma

Ependymomas are enhancing intraventricular tumors arising from the ependymal lining. They are commonly enhancing and conform to the ventricles and the ventricular outflow tract, which results in their description of “toothpaste” like lesions. In adults, they most commonly occur in the 4th ventricle although in pediatric patients they can occur elsewhere.

When in the posterior fossa, your main differential is choroid plexus papilloma/tumor. If you can’t tell that it’s an intraventricular lesion it can be harder because the differential diagnosis also include metastatic disease and possibly medulloblastoma. If you see a lesion that looks similar but doesn’t enhance very much, think about it’s sister lesion subependymoma.