Diagnostic Criteria

Because schwannomatosis can be difficult to diagnose, it’s important to know that an accurate diagnosis of the disorder can only be made by a physician with expertise in the diagnosis and treatment of neurofibromatosis. Specific diagnostic criteria have been established based on a consensus of experts¹. 

Molecular Diagnosis

• Two or more pathologically proved schwannomas or meningiomas AND genetic studies of at least two tumors with loss of heterozygosity (LOH) for chromosome 22 and two different NF2 mutations; if there is a common SMARCB1 mutation, this defines SMARCB1-associated schwannomatosis
• One pathologically proved schwannoma or meningioma AND germline SMARCB1 pathogenic mutation

Clinical Diagnosis

• Two or more non-intradermal schwannomas, one with pathological confirmation, including no bilateral vestibular schwannoma by high-quality MRI (detailed study of internal auditory canal with slices no more than 3mm thick). Recognize that some mosaic NF2 patients will be included in this diagnosis at a young age and that some schwannomatosis patients have been reported to have unilateral vestibular schwannomas or multiple meningiomas.
• One pathologically confirmed schwannoma or intracranial meningioma AND affected first-degree relative
• Consider as possible diagnosis if there are two or more non-intradermal tumors but none has been pathologically proven to be a schwannoma; the occurrence of chronic pain in association with the tumor(s) increase the likelihood of schwannomatosis

Patients with the following characteristics do not fulfill diagnosis for schwannomatosis:

• Germline pathogenic NF2 mutation
• Fulfill diagnostic criteria for NF2
• First-degree relative with NF2
• Schwannomas in previous field of radiation therapy only

1. Plotkin SR, Blakely JO, Evans DG, Hanemann CO, Hulsebos TJ, Hunter-Schaedle K, Kalpana GV, Korf B, Messiaen L, Papi L, Ratner N, Sherman LS, SMith MJ, Stemmer-Rachamimov AO, Vitte J, Giovannini M. 2013 Update from the 2011 International Schwannomatosis Workshop: From genetic to diagnostic criteria. Am J Med Genet Part A 161A:405-416.

Genetic testing is available for the SMARCB1 gene mutation, which is associated with some cases of schwannomatosis. Testing is also offered for another recently identified gene, LZTR1, responsible for some cases. At present, genetic testing does not reveal a mutation in all affected individuals, and there may be additional genes responsible for the disorder in some people yet to be discovered. However, the genetics and inheritance of schwannomatosis is more complex and less clear than for NF1 and NF2. A genetic counselor can provide guidance and information regarding the suitability of genetic testing.

Treatment and Medical Management

Because there is currently no cure for schwannomatosis, treatment and medical management of the condition often focuses on surgery to remove schwannomas (nerve tumors) and lessen the associated nerve pain. Complete removal of the tumors often helps pain to subside, although the pain may recur if other tumors form. For management of chronic pain that is often associated with schwannomatosis, treatment administered in a multidisciplinary pain clinic is often recommended.