Malignant peripheral nerve sheath tumour

Malignant peripheral nerve sheath tumours (MPNSTs) are forms of peripheral nerve sheath tumours and comprise of malignant forms of neurofibromas and schwannomas

They are estimated to account for 5-10% of all soft-tissue sarcomas. They typically present in adults. There is no recognised gender predilection and clinical presentation varies dependant on location. 

They can either arise de-novo or de-differentiate from an exising neurofibroma or schwannoma. 


Tumours commonly occur close to a plexus of nerve trunk, e.g. sacral plexus/brachial plexus.


Imaging criteria are generally considered unreliable in differentiating from a more benign neurofibroma or schwannoma 4. However general rules favouring a MPNST include:

  • the larger the lesion, the more likely for it to be malignant
  • irregular borders (although most MPNSTs can have well defined margins)
  • rapid growth on interval imaging
  • T1: usually isointense to muscle 4; heterogeneous signal on T1 (if present) may useful in differentiating from a neurofibroma 3
  • T2: can have low signal due to high collagen content 4

Gallium67 scintigraphy may show higher uptake than that of a neurofibroma 6-7.

It is an aggressive tumour that carries an extremely poor prognosis.

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Article Information

rID: 11066
Synonyms or Alternate Spellings:
  • Neurofibrosarcoma
  • Malignant schwannoma
  • Neurofibrosarcomas
  • Malignant schwannomas
  • MPNST's

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    Case 4: left V1 involving supra-orbital and frontal branches
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    Case 5: malignant schwannoma
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