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Neurofibromatosis Type 2


KEY FACTS

Terminology

  • Rare autosomal dominant disease from chromosomal 22 defect in which all patients develop CNS tumors

  • Mnemonic for NF2 tumors: M ultiple i nherited s chwannomas, m eningiomas, and e pendymomas (MISME)

Top Differential Diagnoses

  • Metastases

  • Hemangioblastomas

  • Nonsyndromic schwannoma

  • Nonsyndromic meningioma

  • Nonsyndromic ependymoma

  • Lymphoma

Pathology

  • 22q12 deletion correlates with loss of NF2 gene product “merlin” (a.k.a. schwannomin)

  • Definite diagnosis of NF2

    • Bilateral CN8 (vestibular) schwannomas

    • 1st-degree relative with NF2 and either unilateral early-onset vestibular schwannoma (age < 30 years) or any 2: Meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity

  • Presumptive diagnosis of NF2

    • Early-onset unilateral CN8 schwannomas (age < 30 years) and 1 of the following

      • –

        Meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity

      • –

        Multiple meningiomas (> 2) and unilateral vestibular schwannoma

    • Or 1 of these: Glioma, schwannoma, juvenile posterior subcapsular lenticular opacity

Clinical Issues

  • Minimal to no cutaneous stigmata

Diagnostic Checklist

  • Screen using MR C+ of brain and entire spine

  • Imaging follow-up of patients with spinal tumors should be based on knowledge of tumor location, number, and suspected histologic type

Sagittal graphic illustrates multiple rounded schwannomas (brown)
along the cauda equina, as well as flat dural-based meningiomas (red)
impinging the conus.

Axial T1WI C+ MR shows bilateral enhancing cerebellopontine angle masses
due to vestibular schwannomas in this patient with neurofibromatosis type 2.

Sagittal T1WI C+ MR demonstrates multiple intramedullary enhancing ependymomas. The largest is at the C3-C5 level
, with an associated inferior cyst
, with a smaller 2nd tumor at C7-T1 level
.

Axial T1 C+ MR shows heterogeneous enhancement of paraspinal schwannomas
, as well as an intradural extramedullary tumor with a broad dural base consistent with meningioma
.

TERMINOLOGY

Abbreviations

  • Neurofibromatosis type 2 (NF2), nonsyndromic (NS)

Synonyms

  • Bilateral acoustic neurofibromatosis, central neurofibromatosis (both obsolete)

Definitions

  • Autosomal dominant disease from chromosomal 22 defect in which all patients develop CNS tumors

  • Mnemonic for NF2 tumors: M ultiple i nherited s chwannomas, m eningiomas, and e pendymomas (MISME)

IMAGING

General Features

  • Best diagnostic clue

    • Multiple spinal tumors of various histologic types

  • Location

    • Schwannomas

      • –

        Intradural, extramedullary; occur anywhere

      • –

        Rarely intramedullary; arise primarily or secondarily extend from nerve root tumor

      • –

        May extend extradurally

    • Meningiomas: Intradural, extramedullary; typically involving thoracic spine, but occur anywhere

    • Ependymomas: Intramedullary; typically upper cervical cord or conus, but occur anywhere

  • Size

    • Schwannomas: Tiny to several cm

    • Meningiomas: Vary from large to nodular studding

    • Ependymomas: Tiny to a few cm

  • Morphology

    • Schwannomas

      • –

        Rounded, cystic when large, near a nerve root

      • –

        Dumbbell-shaped when extends extradurally

    • Meningiomas: Flattened with dural attachment

    • Ependymomas: Rounded

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