Schwannomatosis

Schwannomatosis, also known as neurilemmomatosis, is a condition characterised 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.

Diagnostic criteria
  • two or more non intradermal (cutaneous) schwannomas

    • at least one with pathological confirmation

  • no evidence of any vestibular tumour (it demands high-quality imaging of the vestibular nerves)

  • no known NF-2 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 haemorrhage. 

CT 
  • Schwannomas are usually slightly hypo to isodense to skeletal muscle with varying degrees of enhancement.
    • small tumours show homogeneous enhancement
    • larger tumours may show heterogeneous enhancement
  • adjacent bone remodeling may be seen
MRI
  • Typical signal characteristics:
    • T1 - isointense or hypointense
    • T2 - hyperintense
    • T1 C+ (Gd) - intense enhancement
  • cystic and fatty degeneration are common 
  • haemorrhage occurs in 5% of cases 
  • calcification is rare
  • peripheral arachnoid cysts may be associated

Symptom control with pain relief. 

Asymptomatic patients are followed and observed.  

When occurs spinal cord compression or symptoms clearly secondary to a schwannoma, surgical intervention is indicated.

 

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Article Information

rID: 10720
Synonyms or Alternate Spellings:
  • Neurilemmomatosis

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