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CASE REPORT Table of Contents   
Year : 2009  |  Volume : 52  |  Issue : 1  |  Page : 74-76
Malignant peripheral nerve sheath tumor with divergent differentiation

1 Department of Pathology, Sri Devaraj Urs Medical College, Sri Devaraj Urs University, Tamaka, Kolar 563 101, India
2 Department of Surgery, Sri Devaraj Urs Medical College, Sri Devaraj Urs University, Tamaka, Kolar 563 101, India

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A malignant peripheral nerve sheath tumor (MPNST) is an uncommon spindle cell sarcoma accounting for approximately 5% of all soft tissue sarcomas. A 55-year-old female with a right suprarenal tumor showed MPNST with additional foci of epithelioid, rhabdomyoblastic, osteogenic and lipogenic differentiation. Although the capacity of MPNST to undergo epithelioid, rhabdomyoblastic, osteogenic and very rarely lipogenic differentiation is reported in literature, the occurrence of all these differentiation in one case has not been described in literature before. To the best of our knowledge, this is only the second MPNST case with lipomatous differentiation

Keywords: Divergent differentiation, epithelioid MPNST, malignant triton tumor, malignant peripheral nerve sheath tumor

How to cite this article:
Suresh T N, Harendra Kumar M L, Prasad C, Kalyani R, Borappa K. Malignant peripheral nerve sheath tumor with divergent differentiation. Indian J Pathol Microbiol 2009;52:74-6

How to cite this URL:
Suresh T N, Harendra Kumar M L, Prasad C, Kalyani R, Borappa K. Malignant peripheral nerve sheath tumor with divergent differentiation. Indian J Pathol Microbiol [serial online] 2009 [cited 2023 Sep 26];52:74-6. Available from:

   Introduction Top

A malignant peripheral nerve sheath tumor (MPNST) is a spindle cell sarcoma arising from Schwann cells or within neurofibromas. MPNST accounts for approximately 5% of all soft tissue sarcomas. [1] About half of these tumors arise denovo and the other half has a strong association with Type 1 Von Recklinghausen's disease. The capacity of peripheral nerve sheath sarcomas to exhibit other than Schwannian or fibroblastic differentiation was first reported by Garre in 1892. [2] We report an unusual case of MPNST with epithelioid, rhabdomyoblastic, osteogenic and lipogenic differentiation.

   Clinical Summary Top

A 55-year-old female presented with a gradually enlarging abdominal mass of 2 years duration associated with pain for the past 6 months. On examination, a firm irregular mass was seen in the right lumbar region. There was no evidence of Von Recklinghausen's disease. An ultrasonography and computed tomography (CT) scan showed a large heterodense solid mass with areas of calcification and necrosis in the right supra renal region. Pre-operatively, the mass couldn't be easily separated from the kidney; hence the excision of the suprarenal mass with right nephrectomy was done.

Pathological findings

A gross examination showed a large encapsulated grey-brown tumor in the upper pole of the kidney measuring 20 x 15 x 12 cm. The surface was bosselated with nodular areas. A cut section showed white, fleshy, lobular tumour tissue with extensive areas of hemorrhage and necrosis. The tumor was separated from the kidney by a capsule. The right kidney measured 11 x 6 x 5 cm. A cut section showed no gross abnormalities.


The neoplasm was predominantly composed of spindle cells arranged in interlacing fascicles, whorls and a palisiding pattern [Figure 1A]. The tumor showed variable cellularity consisting of densely cellular fascicles alternating with hypocellular and myxoid areas. Spindle cells showed hyperchromatic nuclei with indistinct pale cytoplasm and increased mitotic activity (6 per high power field). A few round plump cells with brightly eosinophilic cytoplasm and hyperchromatic nuclei were seen admixed with neoplastic spindle cells [Figure 1A], inset.

The other predominant tumor cell type was large round to polygonal cells with acidophilic cytoplasm and prominent nucleoli giving an epithelioid-like appearance [Figure 1B]. These cells were arranged in nodules, sheets, or in a nesting pattern-mimicking pheochromocytoma-like areas. Hence, in the early evaluation of this tumor, a possibility of MPNST with pheochromocytoma (composite pheochromocytoma) was considered, but subsequent immunohistochemistry excluded this possibility.

In addition, focal areas of osteogenic differentiation [Figure 1C], lipomatous tissue [Figure 1D] and myxomatous change were also seen. On histology, the kidney showed no significant morphological abnormalities.

Immunohistochemistry stains using S-100, Desmin, Myo D1 (myogenic determination) and chromogranin antibodies were done. S-100 showed focal positivity in spindle cell areas. Epithelioid-like areas showed diffuse and strong positivity for S-100 [Figure 2A] and negative for chromogranin antibodies suggesting an epithelioid type of MPNST and ruled out the possibility of composite pheochromocytoma (MPNST with pheochromocytoma). Round plump cells showed positivity for Desmin and Myo D1 [Figure 2B] suggesting rhabdomyosarcomatous differentiation.

   Discussion Top

MPNSTs are uncommon spindle cell sarcomas that appear in the setting of neurofibromas or schwannomas and are associated with peripheral nerves. The estimated incidence of MPNST in patients with Nerurofibromatosis Type 1(NF1) is 2-5% as compared with 0.001% in the general population. The most common anatomical sites include proximal portions of upper and lower extremities, the trunk arising from the sciatic, the brachial plexuses and the sacral plexuses, respectively. Most MPNSTs are high-grade sarcomas with a high likelihood of producing local recurrences and distant metastasis. Large tumor size (>5 cm), the presence of neurofibromatosis and a total resection are the most important prognostic indicators of MPNST. [3] Structural abnormalities of chromosome 17 involving the NF1 and p53 loci are common in MPNSTs.

MPNSTs occasionally show histological evidence of focal divergent differentiation to rhabdomyosarcoma, osteosarcoma, chondrosarcoma, angiosarcoma, epithelial elements or in combination. Ducatman, et al. noted divergent differentiation in 19 out of 120 MPNST cases (19%) and the presence of divergent differentiation did not significantly affect the prognosis. [3] Mature islands of bone and cartilage are the most common heterologous elements in MPNSTs.

Malignant triton tumor (MTT) refers to MPNSTs with rhabdomyosarcomatous differentiation. Rhabdomyosarcoma is the most frequently encountered example of divergent differentiation in MPNSTs. [4] Nearly 70% of patients with MTT have NF 1 and the prognosis is poor as compared with classical MPNSTs with 2 and 5-year survival rates of approximately 33% and 12% respectively. [5]

Less than 5% of MPNSTs show epithelioid differentiation. Epithelioid-like components show strong positivity for S-100 as compared with focal positivity seen in classical MPNSTs. They show less association with NF1. [6] Interestingly, most of the MPNSTs that have arisen from the malignant transformation of benign Schwannoma have been of the epithelioid type.

A few cases of MPNST with foci of glandular differentiation are reported in the literature. [7] A total of 75% of patients have NF 1 with a high mortality rate. A single case of MPNST with liposarcomatous component is noted in the literature. [8]

The finding of these heterotrophic elements in nerve sheath sarcomas is believed to illustrate the differentiating capacity of neuroectodermal tissue. The occurrence of mesenchymal differentiation in primary tumors of the central nervous system, such as intracerebral and meningeal rhabdomyosarcomas, gliomas with muscle, bone and cartilage provide additional supportive evidence. [9],[10]

Although the capacity of MPNSTs to undergo epithelioid, rhabdomyoblastic, osteogenic and very rarely lipogenic differentiation is reported in literature, the occurrence of all these differentiation in the same case has not been not described in literature before. To the best of our knowledge, this is only the second MPNST case with lipomatous differentiation. Diagnostically, it is crucial to recognize the "primary" sarcoma in such tumors correctly and distinguish it from the "secondary" divergent elements, so as to avoid diagnostic errors.

   Acknowledgement Top

We thank Dr. S.K. Shankar, Professor of Neuropathology, NIMHANS, Bangalore for immunohistochemistry and Dr. Krishna Prasad, Professor of Surgery, for reviewing the manuscript.

   References Top

1.Lowis JJ, Brennan MF. Soft tissue sarcomas. Curr Probl Surg 1996;33:817-72.  Back to cited text no. 1    
2.Garre C. Ueber sekundar Maligne Neurome. Beitr Klin Chir 1892;9:465-95.  Back to cited text no. 2    
3.Ducatman BS, Scheithauer BW, Piepgras DG, Reiman HM, Ilstrup DM. Malignant peripheral nerve sheath tumors: A clinicopathologic study of 120 cases. Cancer 1986;57:2006-21.  Back to cited text no. 3  [PUBMED]  
4.Stasik CJ, Tawfik O. Malignant Peripheral Nerve Sheath Tumor with rhabdomyosarcomatous differentiation (Malignant Triton Tumor). Arch Pathol Lab Med 2006;130:1878-81.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.Brooks JS, Freeman M, Enterline HT. Malignant Triton Tumors. Natural history and immunohistochemistry of nine new cases with literature review. Cancer 1985;55:2543-9.  Back to cited text no. 5    
6.Laskin WB, Weiss SW, Bratthauer GL. Epithelioid variant of Malignant peripheral nerve sheath tumor (Malignant epithelioid sachwannoma). Am J Surg Pathol 1991;15:1136-45.  Back to cited text no. 6  [PUBMED]  
7.Nagasaka T, Lai R, Sone M, Nakashima T, Nakashima N. Glandular malignant peripheral nerve sheath tumor: An unusual case showing histologically malignant glands. Arch Pathol Lab Med 2000;124:1364-8.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]
8.D'Agostino AN, Soule EH, Miller RH. Primary malignant neoplasm of nerves (malignanat neurilemomas) in patients without manifestation of multiple neurofibromatosis (Von Recklinghausen's disease). Cancer 1963;16:1003.  Back to cited text no. 8  [PUBMED]  
9.Mathews T, Moossy J. Gliomas containing bone and cartilage. J Neuropathol Exp Neurol 1974;33:456-71.  Back to cited text no. 9  [PUBMED]  
10.Leedham PW. Primary cerebral rhabdomyosarcoma and problem of medullomyoblastoma. J Neurol neurosurg Pschiatry 1972;35:551-9.  Back to cited text no. 10    

Correspondence Address:
T N Suresh
Department of Pathology, Sri Devaraj Urs Medical College, Sri Devaraj Urs University, Tamaka, Kolar 563 101
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.44971

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  [Figure 1A], [Figure 1B], [Figure 1C], [Figure 1D], [Figure 2A], [Figure 2B]

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