• 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

• 40 year old man with lower back pain (Iran J Kidney Dis 2011;5:373)
• 64 year old man with retroperitoneal tumor (Hinyokika Kiyo 2007;53:619)
• 71 year old man with tumor arising from greater omentum (World J Surg Oncol 2011;9:33)
• Arising from neurofibroma in NF1 patients (Cases J 2009 Jun 9;2:7612)

Greater omentum

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

Large, yellow-tan

Firm, grey-white

• 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

Various images

Various images

Epithelioid cells

Plexiform

Various stains

• CD99/O13 (86%), S100 (62%), CD57 (55%), collagen IV, p53
• Leu7/CD57 in neurofibroma-like areas
• Protein gene product 9.5 is more sensitive than S100 but not specific (Arch Pathol Lab Med 2001;125:1321)

• EMA (usually), keratin (usually), CD19

• Infoldings of cell membrane with lamellar configuration, discontinuous basal lamina, conspicuous intercellular junctions, occasional dense-core granules

• t(X;18) negative (Mod Pathol 2002;15:589)

• MFH
• Pleomorphic liposarcoma
• Synovial sarcoma: usually CK7+, CK19+ (Am J Clin Pathol 1999;112:641)

• 5% of MPNST
• Plump epithelioid cells with acidophilic cytoplasm
• Most neurofibromas with malignant transformation are epithelioid, but most epithelioid MPNST are NOT associated with NF1

• 62 year old man with painful mass in third web space of foot (Case Rep Oncol Med 2011;2011:705345)
• 63 year old woman with palpable vulvar mass (J Korean Med Sci 1997;12:78)
• 84 year old woman with mass in medial canthus (eye) (Jpn J Ophthalmol 2004;48:565)

Foot #1

#2

Site unspecified: Fig 2 & 3a

Foot

• Protein gene product 9.5 is sensitive not specific (Arch Pathol Lab Med 2001;125:1321), nerve growth factor receptior, S100 (often, Am J Surg Pathol 2001;25:13)

• INI1 (50%, Am J Surg Pathol 2009;33:542), cytokeratin , HMB45 (usually)

• Epithelioid angiosarcoma: CD31+, CD34+, vWF+, S100-
• Melanoma

• MPNST with well developed skeletal muscle component

1. Tumor arises along a peripheral nerve, in a ganglioneuroma, in NF1 patient, or is a metastasis from such a tumor
2. Tumor has characteristics of Schwann cell tumor
3. Rhabdomyoblasts arise from body of tumor

• 32 year old man with epigastric pain and retroperitoneal mass (World J Surg Oncol 2012;10:96)
• 40 year old man with gluteal mass (Case Rep Neurol 2010;2:69)

Buttock mass

Retroperitoneal tumor

Rhabdomyoblastic differentiation

Cerebellopontine angle

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