maligner peripherer Nervenscheidentumor (MPNST)

MRI image
showing the site of the tumor in the left tibia
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School ager
with a rapidly enlarging soft tissue mass of the right chest and armCXR PA and lateral shows a right apical thoracic mass with associated rib thinning that had rapidly increased in size in a short interval. Axial CT without contrast of the chest better defined the right apical mass and demonstrated multiple serpiginous nodules in the soft tissues of the right anterior chest wall.The diagnosis was degeneration of a plexiform neurofibroma into a malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1.
pediatricimaging.org • CC-by-nc-sa 4.0
The more you
look the more you find: imaging observations of lumbosacral Malignant Peripheral Nerve Sheath Tumor. Contrast-enhanced CT scans showed no enhancement during the arterial phase.
www.eurorad.org • CC by-nc-sa-4.0
The more you
look the more you find: imaging observations of lumbosacral Malignant Peripheral Nerve Sheath Tumor. Conventional T1-weighted scan showed inhomogeneous iso-/hyper- intense mass.
www.eurorad.org • CC by-nc-sa-4.0
The more you
look the more you find: imaging observations of lumbosacral Malignant Peripheral Nerve Sheath Tumor. The early venous phase THRIVE scans showing progressive contrast enhancement of the lesion.
www.eurorad.org • CC by-nc-sa-4.0
The more you
look the more you find: imaging observations of lumbosacral Malignant Peripheral Nerve Sheath Tumor. SPIR in the delayed phase, in order to the fatty tissue component suppression, allowed to characterise the central foci as hemoglobin catabolites.
www.eurorad.org • CC by-nc-sa-4.0
The
diagnostic pitfalls of lumbar disc herniation---- malignant sciatic nerve tumour: two case reports and literature review. Gluteal MRI in case 2. a Coronal MRI shows a fusiform tumour in the femoral region (arrow). b T2-weighted axial MRI shows a mixed low- and high-intensity signal (arrow)
bmcmusculoskeletdisord.biomedcentral.com • CC-by-4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Malignant peripheral nerve sheath tumors (MPNSTs) are forms of peripheral nerve sheath tumors and comprise of malignant forms of neurofibromas and schwannomas. Approximately half of such tumors are seen in individuals with neurofibromatosis type I (NF1), in such cases arising from pre-existing neurofibromas.

Epidemiology

Malignant peripheral nerve sheath tumors are estimated to account for 5-10% of all soft-tissue sarcomas. They typically present in young and middle-aged adults . There is no recognized gender predilection. When seen in the setting of NF1, they tend to occur in younger patients . They are also encountered with greater frequency in individuals who have previously received radiotherapy .

Clinical presentation

Clinical presentation varies depending on location.

Pathology

MPNSTs can either arise de-novo or de-differentiate from an existing neurofibroma (most often plexiform neurofibromas in NF1) or rarely other neurogenic tumors (e.g schwannoma, ganglioneuroblastoma, ganglioneuroma, pheochromocytoma) .

Location

MPNSTs usually arise from a large nerve, and thus usually occur close to a plexus (e.g. sacral plexus/brachial plexus). Cranial nerves are rarely involved, and on the rare occasions they are, then the MPNST has usually arisen from an underlying schwannoma rather than a neurofibroma .

Genetics

Most MPNSTs demonstrate inactivation of a number of genes: NF1, CDKN2A, and PRC2 .

Macroscopic appearance

The macroscopic appearance depends both on location and on whether or not the MPNST has arisen from an underlying pre-existing tumor. They are often large (>5 cm) at diagnosis, and may demonstrate local infiltration into surrounding tissues .

Microscopic appearance

The microscopic appearance of MPNSTs is heterogeneous, varying in cellularity and growth pattern, generally including tightly packed spindle cells arranged in either a herringbone or interwoven fasciculated pattern .

Immunophenotype

Immunohistochemistry reflects their neurogenic origin, with the following immunoreactivity :

  • S100: positive in 50-70% - low in high-grade MPNSTs
  • p53 protein: positive in 75%
  • EGFR: positive in ~35%
Variants

A number of histological variants are recognized :

  • epithelioid MPNST
  • MPNST with divergent differentiation (aka malignant triton tumor)
  • MPNST with perineural differentiation (aka malignant perineurioma)

Radiographic features

Imaging criteria are generally considered unreliable in differentiating from a more benign neurofibroma or schwannoma . However, general rules favoring an 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 in interval imaging
MRI
  • T1
    • usually isointense to muscle
    • a heterogeneous signal on T1 (if present) may useful in differentiating from a neurofibroma
  • T2
    • can have low signal due to high collagen content
Scintigraphy

Gallium scintigraphy may show higher uptake than that of a neurofibroma .

Treatment and prognosis

It is an aggressive tumor that carries a poor prognosis, with 20-25% of patients developing metastases . Poor prognostic factors include :

  • NF1
  • large size
  • location on the trunk
  • high-grade histological features
Siehe auch:
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Assoziationen und Differentialdiagnosen zu maligner peripherer Nervenscheidentumor (MPNST):
Neurofibromatose
Typ 1
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Schwannom
 
www.eurorad.org • CC by-nc-sa-4.0
benigner
peripherer Nervenscheidentumor
www.eurorad.org • CC by-nc-sa-4.0
Neurofibromatose
Typ 1 und Neurofibrosarkom
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