Findings
MRI of the brain demonstrates multiple extraaxial enhancing mass lesions throughout the brain. The largest of these lesions is near the splenium of the corpus collusum in a posterior left sagittal location. Lesions are noted extending into the falx cerebri, tentorium and convexity dura. Smaller lesions are also identified in the left cerebellopontine angle, sphenoid wings bilaterally, within the sylvain fissures and adjacent to the transverse sinus. The lesions are slightly hyperintense to brain matter on proton density and T2 weighted images.
Differential diagnosis for extraaxial lesions in the brain
- Meningioma
- Schwannoma
- Metastases
- Epidermoids, Dermoids, Teratomas
- Lipomas
- Arachnoid cyst
- Choroid plexus papillomas
- Lymphoma
Diagnosis: Multiple meningiomas in Neurofibromatosis Type 2
Key points
Remember the imaging characteristics of an extraaxial mass:
1) grey-white matter buckling
2) expansion of the ipsilateral subarachnoid space
3) reactive bony changes
Nerve sheath/meningeal tumors (schwannomas, meningiomas, ependymonas) predominate in NF2 and glial type tumors (gliomas, neurofibromas) predominate in NF1.
Look for other tumors elsewhere (e.g., ependymomas) when confronted with NF2.