Neuroradiology Board Review – Brain Tumors – Case 12
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.
In this case, you first see a CT with a hyperdense mass anterior to the frontal horn of the left lateral ventricle. On MRI, you see a somewhat nodular appearing mass with a rim of hypointensity on T2. Centrally, there are areas of T1 and T2 hyperintensity. On postcontrast, there is minimal if any enhancement, best seen on the 3D postcontrast images.
The diagnosis is: cavernous malformation
Cavernous malformations are benign collections of disorganized blood vessels. They have previous names, including cavernoma and cavernous hemangioma, but these have fallen out of favor because these lesions do not have a proliferative component.
On imaging, these are characterized as “popcorn” like masses with a rim of hemosiderin. They usually have areas of T1 and T2 hyperintensity centrally. Classically they are described as non-enhancing, but in my experience it is relatively common (maybe 25-30% of the time), probably because of the increase in thin-slice 3D imaging. Cavernous malformations can be isolated (about 2/3 of cases) or familial (the remaining 1/3). Familial cavernous malformation are associated with mutations in the KRIT or CCM genes. There is a relatively low annual risk of hemorrhage from these lesions (about 0.25-0.75% per year for single lesions or 1% per year per lesion for familial cavernous malformations).
Cavernous malformations can mimic hemorrhage, particularly if the history is trauma. CT sometimes has calcification, which can be a nice clue. Otherwise, the lack of symptoms and lack of edema can help you. Sometimes, you may need an MRI or a delayed CT follow-up (24-48 hours later) to show that it is stable and prove it is not a hemorrhage.
Often cavernous malformations have an associated developmental venous anomaly adjacent to them. This is a venous structure which has a tree-like branching pattern and otherwise resembles a normal vein. These can sometimes be large and confuse people into thinking it is an arteriovenous malformation, but there is no shunting.