So, humbly, I’ll make some opening remarks. This is a coronal section of a T1WI enhanced with gado revealing a large homogenously enhancing mass extending from the brainstem up past the midbrain and encroaching on the inferomedial temporal lobes bilaterally. There is no active hemorrhage within the mass, nor are there enhancing borders which makes this lesion less worrisome for a GBM. There is also mass effect with uncal herniation (hence the CN III palsy). I’m willing to bet this child also had a degree of clumsiness/new-found stumbling and if it were not for the CN III palsy she most probably would not have any idea she had this ugly-looking lesion sitting on her brainstem. Differentials I’ll include are fibrillary astrocytoma, JPA, and pontine glioma/AA/GBM. This lesion also demonstrates large flow-voids which are also concerning. Please comment further guys....

Looks like a craniopharyngioma.

looks like a large mass probably growing from the sella/anterior fossa floor.  Would need more imaging such as a sagital to show definitively its not in the brainstem like the previous poster suggests.  Craniopharyngioma is definitely one possibility or some other ugly sella region mass.  I’m not worried about the flow voids… I think they are normal vessels being incorporated.  JPA is possible, could have come from optic nerve or hypothalamus, but usually cystic.  I still thank Craniopharyngioma is highest on my list like the other poster suggested.

My first thought was craniopharyngioma as well, but shouldn’t there be a cystic component?  What about meningioma or even macroadenoma?

I posted right before you.  Could be a large olfactory groove meningioma.  I agree pituitary macroadenoma is also possible.

How would you treat it.

If it does extend into the sella… you probably have to do both a transphenoidal and open craniotomy (two separate surgeries).

This is why I’d never want to be a tumor surgeon.

I think that it is important to remember that ths patient needs a complete pituitary workup prior to anything. Definitely in the differential is cranio, but they are usually cystic, but things like pituitary tumor, JPA (chiasmatic or optic), or even meningioma.  Other less likely things include lymphoma, germ cell tumor, or infectious or inflammatory lesions, such as sarcoid, TB, histiocytosis.  I would be very curious to see what the prolactin is.  I think that if you are going to operate, the first step is biopsy, prior to any other surgical treatment.  As to surgical treatment, the sellar portion could be worried about at a later date.  Pretty insignificant compared to the rest, don’t you think?  I think it is important to not get worked up by the size of the mass.  Be thorough, because you may not even need to operate (or just do a biopsy), if it is something like a prolactinoma, germ cell tumor, or histiocytosis, lymphoma.