Neurofibromatosis type II
Findings:
Axial and coronal postcontrast T1 weighted images show
bilateral enhancing masses at the cerebellopontine angle which extend into
and expand the internal auditory canals. Sagittal images of the spine show
an extramedullary intradural lesion at the level of L2-3 and intramedullary
enhancing lesions in the cervical cord and pons.
Differential Diagnosis:
The finding of bilateral acoustic neuromas is pathognomonic
for NF2. Meningiomas may have similar enhancement characteristics but they
do not extend into the IAC.
Discussion:
Neurofibromatosis type II is also known as MISME (multiple
inherited schwannomas, meningiomas, ependymomas), and is an autosomal dominant
phakomatosis localized to chromosome 22. Up to 50% represent new mutations.
Unlike NF1, skin manifestations are minimal. The diagnostic criteria include
either bilateral VIII nerve masses or relative with NF2 and unilateral
VIII mass or two of the following: neurofibroma, meningioma, glioma, schwannoma,
or congenital lens opacity. Ependymomas are most common in spinal cord
(80%), and most are multiple. Of spinal schwannomas, most are intradural
extramedullary (70%)