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)
- neurofibromatosis type I - in 25-70% of cases
- previous irradiation
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 MPNST's can have well defined margins)
- rapid growth on interval imaging
- T1 : usually iso intense to muscle 4; heterogenous signal on T1 (if present) may useful in differentiating from a neurofibroma 3
- T2 : can have low signal due to high collagen content 4
Gallium 67 scintigraphy may show higher uptake than that of a neurofibroma 6-7
Treatment and prognosis
It is an aggressive tumour that carries an extremely poor prognosis.
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- 5. Murphey MD, Smith WS, Smith SE et-al. From the archives of the AFIP. Imaging of musculoskeletal neurogenic tumors: radiologic-pathologic correlation. Radiographics. 19 (5): 1253-80. Radiographics (full text) - Pubmed citation
- 6. Hrehorovich PA, Franke HR, Maximin S et-al. Malignant peripheral nerve sheath tumor. Radiographics. 23 (3): 790-4. doi:10.1148/rg.233025153 - Pubmed citation
- 7. Levine E, Huntrakoon M, Wetzel LH. Malignant nerve-sheath neoplasms in neurofibromatosis: distinction from benign tumors by using imaging techniques. AJR Am J Roentgenol. 1987;149 (5): 1059-64. AJR Am J Roentgenol (abstract) - Pubmed citation
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