Neurofibromatosis type 2

Clinical History

The patient presented with sudden unconsciousness. The patient had suffered from severe headache and decreased hearing for a long time.

Imaging Findings

MRI brain revealed bilateral cerebellopontine angle extra-axial lesions with internal auditory canal extension. On post-contrast study the lesions showed intense enhancement. Both lesions extended into the jugular fossa. Internal haemorrhage was seen in the left-sided lesion. Both lesions were causing severe compression over pons. This suggested bilateral acoustic schwannoma.
Multiple intensely enhancing extra-axial lesions were seen in the left frontal region, falcine region, left petrous region. The lesions showed intense enhancement on post-contrast study. All lesions were broad-based towards the dura with dural tail enhancement on post-contrast study. The left frontal lesion was large and caused mass effect. This suggest multiple meningiomas.

Discussion

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant neurocutaneous disorder (phakomatosis) manifesting as development of multiple CNS tumours. [1, 2, 3]
Neurofibromatosis type 2 is also known as central neurofibromatosis or bilateral acoustic schwannomas or MISME syndrome (Multiple Inherited schwannomas, meningiomas and ependymomas ). [4] In fact, labelling this disorder neurofibromatosis type 2 is a misnomer, because neurofibromas are not a part of its constellation of abnormalities. [4]
The neoplasms usually develop in adult patients - but the predisposition is inherited via a mutational loss of a tumour supressor gene on the long arm of chromosome 22. This gene codes for a protein pNF2 or "schwannomin" - also called "merlin". Although meningiomas are often an isolated findings in adults, their presence in a child should raise suspicion regarding NF2. The presence of multiple and different types of spinal tumours also raise high suspicion of NF2. [1, 5]
Cutaneous markers are rarer in NF2 as compared to NF-1. CNS lesions are seen in virtually all cases and include neoplasms, non-neoplastic intra-cranial calcifications and spinal cord nerve root tumours. CN VIII schwannomas are a hallmark of diseases most frequently affecting the 8th nerve complex. Unilateral tumours arise from vestibular nerve but schwannomas can be found involving any cranial nerve from CN III to CN XIII, with CN V as the next most frequently involved. [6]
Intracranial meningiomas found in NF2 are usually multiple and appear as well-circumscribed intensely enhancing extraxial masses with dural attachment. Ependymomas are most common intraparenchymal tumour in NF2. Spinal tumours seen in NF2 include schwannomas, meningiomas and ependymomas. Schwannomas may present as intradural extramedullary masses. Benign intracranial calcifications, particularly of choroids plexus, cerebellar hemispheres and cerebral cortex in association with NF2 are seen. Ocular abnormalities including juvenile posterior subcapsular lenticular opacity, hamartomas of retina and choroids are common. [6]
Diagnostic criteria for NF2
Confirmed (Definite) NF2:
1. Bilateral vestibular schwannomas (VS) (also known as acoustic neuroma)
Presumptive (Probable) NF2:
1. Family history of NF2 (first degree family relative) plus:
2. Unilateral vestibular schwannomas or any two of the following: meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity, juvenile cortical cataract.
Individuals with the following clinical features should be evaluated for NF2:
1. Unilateral VS plus at least two of any of the following: meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacities/juvenile cortical cataract
2. Multiple meningiomas (2 or more) plus unilateral VS or any two of the following: glioma, schwannoma, juvenile posterior subcapsular lenticular opacities/juvenile cortical cataract. [5]

Differential Diagnosis List

Final Diagnosis

Neurofibromatosis type 2

URL:	https://www.eurorad.org/case/12075
DOI:	10.1594/EURORAD/CASE.12075
ISSN:	1563-4086