Schwannomatosis, also known as neurilemmomatosis, is a condition characterized by multiple schwannoma formation but without other criteria to support neurofibromatosis type II (NF2). Some however consider this as a variant of NF2 1.
This article is considering schwannomatosis as an independent disease.
It is a rare disorder of unknown prevalence. The incidence peak is between the ages of 30 and 60 years 4.
Patients frequently present with pain that can, sometimes, be disabling, resulting in a diminished quality of life.
- two or more non intradermal (cutaneous) schwannomas
- at least one with pathological confirmation
- no evidence of any vestibular tumor (it demands high-quality imaging of the vestibular nerves)
- no known NF2 mutation
- usually be >30 years at the time of presentation
Multiple discrete and well-defined round lesions situated along the course of peripheral nerves (peripheral segments of the cranial nerves or paraspinous nerve roots) 5.
The majority of patients demonstrate schwannomas confined to one limb or within five or fewer contiguous spinal segments (segmental schwannomatosis) 5.
The larger a schwannoma is, the more likely it is to show heterogeneity because of cystic degeneration or hemorrhage.
- schwannomas usually slightly hypo to isodense to skeletal muscle with varying degrees of enhancement
- small tumors show homogeneous enhancement
- larger tumors may show heterogeneous enhancement
- adjacent bone remodeling may be seen
- typical signal characteristics:
- T1 - isointense or hypointense
- T2 - hyperintense
- T1 C+ (Gd) - intense enhancement
- cystic and fatty degeneration are common
- hemorrhage occurs in 5% of cases
- calcification is rare
- peripheral arachnoid cysts may be associated
Treatment and prognosis
Symptom control consists of pain relief. Asymptomatic patients are followed and observed.
When symptoms of spinal cord compression occur clearly secondary to a schwannoma, surgical intervention is indicated.
- 1 .Evans DG, Mason S, Huson SM et-al. Spinal and cutaneous schwannomatosis is a variant form of type 2 neurofibromatosis: a clinical and molecular study. J. Neurol. Neurosurg. Psychiatr. 1997;62 (4): 361-6. doi:10.1136/jnnp.62.4.361 - Free text at pubmed - Pubmed citation
- 2. Maccollin M, Chiocca EA, Evans DG et-al. Diagnostic criteria for schwannomatosis. Neurology. 2005;64 (11): 1838-45. doi:10.1212/01.WNL.0000163982.78900.AD - Pubmed citation
- 3. Maccollin M, Woodfin W, Kronn D et-al. Schwannomatosis: a clinical and pathologic study. Neurology. 1996;46 (4): 1072-9. Neurology (full text) - Pubmed citation
- 4. Antinheimo J, Sankila R, Carpén O et-al. Population-based analysis of sporadic and type 2 neurofibromatosis-associated meningiomas and schwannomas. Neurology. 2000;54 (1): 71-6. Pubmed citation
- 5. Koontz NA, Wiens AL, Agarwal A et-al. Schwannomatosis: the overlooked neurofibromatosis?. AJR Am J Roentgenol. 2013;200 (6): W646-53. doi:10.2214/AJR.12.8577 - Pubmed citation