An interesting case of neurofibromatosis-2

Clinical History

A 24-year-old lady presented with gradually progressive hearing loss and tinnitus.

Imaging Findings

After detailed clinical evaluation, she was referred to us for MR imaging of brain and the inner ear (7th - 8 th nerve complex). On MR imaging, she was found to have large infratentorial extra-axial masses in each of the cerebellopontine angle cistern (Fig. 1). These lesions demonstrated avid enhancement on post contrast MR scan and were extending into the internal auditory canal causing widening of the internal acoustic meatus (Fig. 2). These MRI findings of bilateral vestibular schwannomas were sufficient for a definite diagnosis of neurofibromatosis type 2 (NF-2), according to the National Institutes of Health, Manchester, or National Neurofibromatosis Foundation diagnostic criteria. These posterior fossa schwannomas were associated with multiple supratentorial extra-axial dural based masses suggestive of intracranial meningiomas (Fig. 3). She also had a well circumscribed homogeneously enhancing intraconal mass in the right orbit, which was encasing the optic nerve. On contrast enhanced MRI, the optic nerve appeared as a negative defect in relation to the surrounding thickened enhancing optic-nerve-sheath on either side represnting the tram-track sign of optic nerve sheath meningioma (Fig. 4). She also had an intra-parotid well defined mass on the right side (Fig. 5) possibly representing a neurogenic tumour of the facial nerve (neurofibroma/ schwannoma). MR imaging of the spine failed to reveal any spinal tumour.

Discussion

We present the case of a 24 year-old patient with Neurofibromatosis type 2 with bilateral acoustic schwannomas, multiple intracranial meningioma, optic nerve sheath (orbital) meningioma and a intraparotid neuroma.

Neurofibromatosis 2 (NF-2) is an inherited autosomal dominant neurocutaneous syndrome (phakomatosis). It is characterised by development of multiple central nervous system tumours such as multiple schwannomas, meningiomas, and ependymomas. The NF-2 gene is a tumour-suppressor gene which has been mapped to chromosome 22. Impaired function of this gene is thought to be responsible for the development of clinical symptoms. NF-2 is an autosomal dominant genetic trait i.e. it affects both genders equally and that each child of an affected parent has a 50% likelihood of inheriting the gene. Typically, these patients present in the second or third decade of life. According to the National Institutes of Health, Manchester, or National Neurofibromatosis Foundation diagnostic criteria of NF-2 include: [1] Bilateral acoustic schwannoma seen with appropriate imaging techniques (e.g. computed tomography or magnetic resonance imaging; or [2] A first-degree relative with NF2 and either a unilateral acoustic schwannoma or 2 of the following: neurofibroma/ meningioma/ glioma/ schwannoma/ juvenile posterior subcapsular lenticular opacity. Acoustic or vestibular schwannomas are usually the most common cause of presentation. These tumours manifest with progressive hearing loss, tinnitus, headache or vestibular symptomas. In spine, majority of intramedullary spinal tumours are ependymomas and arise in either the upper cervical cord or the conus medullaris. Spinal meningiomas present as intradural extramedullary neoplasms most commonly involving the dorsal spine and often are multiple in number.

Differential Diagnosis List

Final Diagnosis

Head & neck manifestations in a case of NF-2

URL:	https://www.eurorad.org/case/8576
DOI:	10.1594/EURORAD/CASE.8576
ISSN:	1563-4086