• Patients must have a confirmed diagnosis of neurofibromatosis 2 by fulfilling National Institute of Health (NIH) criteria or Manchester criteria, or by detection of a causative mutation in the NF2 gene.

• The NIH criteria include presence of:

⁃ Bilateral vestibular schwannomas, OR

⁃ First-degree relative with NF2 and EITHER unilateral eighth nerve mass OR

⁃ Two of the following: neurofibroma, meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity.

• The Manchester criteria include presence of:

⁃ Bilateral vestibular schwannomas, OR First-degree relative with NF2 and EITHER unilateral eighth nerve mass OR - Two of the following: neurofibroma, meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity OR

⁃ Unilateral vestibular schwannoma AND any two of: neurofibroma, meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity, OR

⁃ Multiple meningiomas (two or more) AND unilateral vestibular schwannoma OR

⁃ Any two of: schwannoma, glioma, neurofibroma, cataract.

• Patients must have measurable disease, defined as at least one cutaneous/subcutaneous schwannoma with the following qualities:

‣ Maximal tumor diameter \> 0.5 cm to \< 4.0 cm that can be accurately measured by electronic calipers

⁃ Up to a maximum of 3 tumors/subject may be injected

⁃ Not located on the face

• Age ≥ 8 years on day 1 of treatment.

• Life expectancy of greater than 1 year

• Lansky/Karnofsky performance status ≥ 60

• Fully recovered from acute toxic effects of any prior chemotherapy, biological modifiers or radiotherapy

• Any neurologic deficits must be stable for ≥1 week

• Patient or parent/legal guardian must be able to provide signed informed consent and assent (as applicable for minors)