Malignant peripheral nerve sheath tumours (MPNST)

MPNST accounts for 5% of all sarcomas. 50% of cases are associate with von Recklinghausen's disease. Two thirds of MPNST arise from neurofibromas, one third arise de novo. Origin from a pre-existing Schwannoma, ganglioneuroma or phaeochromocytoma is rare.

Histopathology

MPNST is composed of spindle cells forming fascicles. Nuclei are tapered. Cellularity is variable, with perivascular accentuation. Heterologous elements (epithelial, rhabdomyoblastic, chondroid, osteoblastic or angiosarcomatous) are present in about 15% of cases.

Immunohistochemistry

S-100	50-90%1, 11/164
Leu-7	50%
MBP	40%
Cytokeratin 1	0/163
Cytokeratin 5/6	0/83
Cytokeratin 7	0/373
Cytokeratin 8/18	6/133
Cytokeratin 13	0/133
Cytokeratin 19	4/423
Cytokeratin 20	0/83
p53	7/164
Collagen IV	10/164

MPNSTs associated with neurofibromatosis-I show evidence of diverse differentiation1:

S-100	13/231
g-NSE	13/201
NGRF	15/201
NF	4/191
EMA	6/201
Cam5.2	6/221
desmin	3/221
SMA	3/201
CD34	5/221
collagen IV	9/191

S-100 immunoreactivity is indicative of Schwannian differentiation, EMA+/collagen IV+/NGFR+//S-100- indicates perineural differentiation, CD34 positivity may be associated with known perivascular fibroblast-like cells. Some cases variously shows morphological and ultrastructural evidence of rhabdomyoblastic2 and cartilaginous differentiation.

Prognosis

MPNST is an aggressive tumour with a five-year survival of 35%.

References

1Histopathology 2001;39:298-309.

2Ordonez, N. G., Tornos, C. Malignant peripheral nerve sheath tumor of the pleura with epithelial and rhabdomyoblastic differentiation: report of a case clinically simulating mesothelioma. Am J Surg Pathol 1997;21:1515-1521.

3Chu, P. G. and L. M. Weiss (2002). "Keratin expression in human tissues and neoplasms." Histopathology 40(5): 403-39. (Summary data from multiple papers)

4 Scheithauer BW, Erdogan S, Rodriguez FJ, Burger PC, Woodruff JM, Kros JM, et al. Malignant peripheral nerve sheath tumors of cranial nerves and intracranial contents: a clinicopathologic study of 17 cases. Am J Surg Pathol. 2009 Mar;33(3):325-38.

This page last revised 3.4.2010.