Soft tissue
Peripheral nerve

Topic Completed: 1 November 2012

Minor changes: 22 October 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Malignant peripheral nerve sheath tumor [title]

See also: epithelioid, malignant triton

Vijay Shankar, M.D.
Page views in 2019: 23,675
Page views in 2020 to date: 21,332
Cite this page: Shankar V. MPNST. website. Accessed October 24th, 2020.
Definition / general
  • Also known as malignant schwannoma
  • Bulky deep-seated tumor usually arising from major nerves in neck, forearm, lower leg, buttock
  • 50% associated with neurofibromatosis (NF), 50% arise de novo
  • May be due to radiation; rarely arise from ganglioneuroma
  • Usually adults
  • High clinical suspicion for MPNST if NF1 patient or tumor arising within anatomic component of a major nerve or contiguous with neurofibroma
  • Recur locally, distant metastases frequent
  • Plexiform variant in children has better prognosis, otherwise cannot predict prognosis
Case reports
Clinical images

Images hosted on other servers:

Greater omentum

Gross description
  • Large mass producing fusiform enlargement of major nerve (often sciatic)
Gross images

Contributed by Mark R. Wick, M.D.

Images hosted on other servers:

Various images

Firm, gray-white

Microscopic (histologic) description
  • Monomorphic serpentine cells, palisading, large gaping vascular spaces, perivascular plump tumor cells, geographic necrosis with tumor palisading at edges, resembling glioblastoma multiforme
  • Frequent mitotic figures
  • May have bizarre cells
  • 15% have metaplastic cartilage, bone, muscle
  • May have glandular differentiation (positive for keratin, EMA, CEA, chromogranin); if so, presume malignant
  • May have melanin in tumor cells, particularly if arise from spinal nerve roots (overlaps with primary melanoma of nerves)
  • Note: some have no discernable Schwannian features at any level
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.



Chondroid differentiation


Melanotic pigmented


Storiform growth

Synovial sarcoma

Case #443




Images hosted on other servers:


Various stains

Positive stains
Negative stains
Electron microscopy description
  • Infoldings of cell membrane with lamellar configuration, discontinuous basal lamina, conspicuous intercellular junctions, occasional dense-core granules
Molecular / cytogenetics description
Differential diagnosis
Board review style question #1
A spindle cell tumor with weak positivity for S100 and strong, diffuse nuclear positivity for TLE1 is most likely which of the following?

A. Cellular schwannoma
B. Fibrosarcoma
D. Synovial sarcoma
Board review answer #1
D. Synovial sarcoma. Although MPNST can be positive for TLE1, strong and diffuse nuclear positivity is seen in synovial sarcoma.
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