|Year : 2015 | Volume
| Issue : 2 | Page : 147-149
Giant sporadic high-grade malignant peripheral nerve sheath tumor: A case report with review of literature
R Sonia Kundu1, S Sudhamani1, V Swapnil Sirmukaddam1, O Stuti Agarwal1, M Amita Rani2, P Amira Dhond1
1 Department of Pathology, School of Medicine, D Y Patil University, Navi Mumbai, Maharashtra, India
2 Department of Periodontology, Swami Devi Dayal Dental College, Haryana, India
|Date of Web Publication||17-Jan-2016|
R Sonia Kundu
Department of Pathology, D Y Patil University School of Medicine, Nerul, Navi Mumbai - 400 706, Maharashtra
Source of Support: None, Conflict of Interest: None
Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon spindle cell sarcomas originating from the pleuripotent cells of neural crest or Schwann cells. Head and neck region, the extremities and peripheral nerve trunk roots are its common locations. Sporadic type is a rare variant than the neurofibromatosis-1 associated type of MPNST. This study presents a case of giant, sporadic, and high-grade MPNST of right shoulder in a 48-year-old female.
Keywords: High-grade sarcoma, malignant peripheral nerve sheath tumor, right shoulder, sporadic, tumor
|How to cite this article:|
Kundu R S, Sudhamani S, Sirmukaddam V S, Agarwal O S, Rani M A, Dhond P A. Giant sporadic high-grade malignant peripheral nerve sheath tumor: A case report with review of literature. Indian J Health Sci Biomed Res 2015;8:147-9
|How to cite this URL:|
Kundu R S, Sudhamani S, Sirmukaddam V S, Agarwal O S, Rani M A, Dhond P A. Giant sporadic high-grade malignant peripheral nerve sheath tumor: A case report with review of literature. Indian J Health Sci Biomed Res [serial online] 2015 [cited 2019 Jul 22];8:147-9. Available from: http://www.ijournalhs.org/text.asp?2015/8/2/147/174256
| Introduction|| |
Malignant peripheral nerve sheath tumor (MPNST) term is given to the malignant proliferation of any nerve sheath cell (endoneural fibroblast, perineural fibroblast, and Schwann cells). MPNST is seen most commonly in the age group of 20-50 years. Three variants are seen viz., sporadic variant, in patients with neurofibromatosis-1 (NF-1), and in patients with prior radiation of peripheral nerve. The estimated incidence in general population is 0.001% as compared to 5-45% in patients with NF-1. , Ten percent of NF-1 patients develop MPNST and will show a poor prognosis. 
| Case Report|| |
A 48-year-old female came with the chief complaint of right shoulder swelling since 6 months, rapidly increasing in size. There was no family history and clinical evidence of NF-1.
The clinical, radiological, and FNAC diagnosis was suggestive of soft tissue sarcoma. The wide tumor excision was done.
On gross, the specimen consisted of partially skin covered soft tissue mass measuring 13 cm × 12 cm × 4 cm comprising the wide excision of the tumor.
Cut section showed a fleshy, gray white, and solid tumor mass with the large areas of hemorrhage and necrosis infiltrating into the surrounding tissue ([Figure 1]: Gross image showing fleshy, gray white, solid tumor mass with large areas of hemorrhage and necrosis).
On microscopy, the tumor cells were arranged in sweeping fascicles ([Figure 2]: H and E, 10× showing dense fascicles of spindled cells).
|Figure 1: Gross image showing fleshy, gray white, solid tumor mass with large areas of hemorrhage and necrosis|
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Densely cellular fascicles alternated with hypocellular myxoid zones which swirled and interdigitated with one another showing marble-like effect.
Individual tumor cells were oval to spindle with hyper chromatic, pleomorphic wavy nuclei, and scant cytoplasm. At places, rosettes-like structures were seen. The intervening stroma showed a sparse mononuclear cell infiltrate and the areas of hemorrhage. The necrosis was also seen in more than 50% of areas. Mitotic count was 6-7/10 high power fields. No lymph node involvement or metastasis was seen.
Based on the above features, the histopathological diagnosis was high-grade MPNST sporadic type.
Swelling recurred twice at the same site, initially after 1-year and again after an interval of 7 months but showed no metastasis. Histopathology of the recurrent masses showed the similar histomorphological features as that of the primary tumor.
| Discussion|| |
MPNST is a subcategory of soft tissue sarcomas of ectomesenchymal origin. They are a rare malignant lesions arising from the major or minor peripheral nerve branches or peripheral nerve fiber sheaths.  Laskinet et al., Ducatman et al. pointed out that the irradiation of peripheral nerve sheath can be one of the etiology of MPNST. In that case, the tumor develops after 10-20 years of the latent period following irradiation. They constitute approximately 11% of MPNST. In our case, there was no history of irradiation to the patient.
Pathogenesis of MPNST is very complex and is not well understood. NF-1 is an autosomal condition resulting from the biallelic NF-1 gene inactivation. The neurofibromin (NF-1 gene product) main function is in reducing the cell signal transduction by accelerating the inactivation of proto-oncogene p21-ras. Thus, NF-1 gene mutation leads to increase in ras signaling, posing the great risk for developing both benign and malignant tumor. NF-1 associated MPNST showed the clinical evidence of café au lait spots, multiple neurofibromas, congenital malformations, or other tumors with positive family history in the majority of cases. Our case was lacking all these features, so it was categorized as a sporadic case.
Various studies reported that the patients with sporadic MPNST are usually older at the time of diagnosis and present at an earlier stage when compared to NF-1 associated MPNST. 
MPNST do not show the strong gender prediction. Sporadic cases are relatively overrepresented as the peripheral limb tumors as compared to axial tumors in NF-1 associated MPNST cases.
Overall 5 years survival rate is said to be better in sporadic cases than in NF-1 associated cases as tumor tends to be larger, deeper, and centrally located in NF-1 cases (60% vs. 32%).
There is no significant difference in tumor volume found in both sporadic and NF-1 associated cases. However, the larger volume tumors (>200 ml) are said to show significantly worse prognosis. 
The time interval to local recurrence and metastasis is significantly shorter in NF-1 associated MPNST than in sporadic cases. 
Factors associated with worse disease-specific survival (DSS) were positive margins and larger size. NF-1-associated and sporadic MPNSTs may be associated with improved DSS when compared with RT-induced tumors. 
For a diagnosis of MPNST, the combination of gross, histopathological, and immunohistochemistry (IHC) is needed. On the basis of cellular differentiation, mitotic count, and tumor necrosis, the tumor can be low or high grade. The high grade tumors have >50% necrosis and more than 5 mitotic figures/10 high power field.  Our case was, therefore, typed as high-grade tumor.
Fisher et al. showed that detecting 18 fluorodeoxyglucose (FDG) by positron emission tomography (PET) was useful in monitoring clinically stable NF-1 patients with plexiform neurofibroma as it can detect which were more likely to grow rapidly.
Brenner et al. showed that NF-1 associated MPNST having the higher uptake during FDG-PET were of worse survival.
The cellular origin and histopathological similarity of MPNST with those of other soft tissue sarcomas lead to many diagnostic difficulties. Differential diagnosis includes fibrosarcoma, dedifferentiated liposarcoma, leiomyosarcoma, monophasic synovial sarcoma, etc. The gross, microscopy, and IHC help in definitive diagnosis of these tumors. 
MPNST is focally or diffusely positive for S-100, vimentin, neuron-specific enolase, and negative for MDMK. S-100 and the number of other antigens such as keratin are used to rule out other tumors such as monophasic synovial sarcoma. P53 immunoreactivity is detected in more than 50% of MPNST in contrast to its absence in neurofibroma. However, no IHC was done in our case as the diagnosis was clear cut and the patient was lost to follow-up.
| Conclusion|| |
In the present case, we have highlighted a sporadic, giant, and high-grade form of MPNST, which is a rare clinical entity, as most of the common MPNST presents with NF-1. The molecular diagnostic methods such as reverse transcriptase polymerase chain reaction, FDG-PET can be used as a novel diagnostic markers and therapeutic targets for the treatment of MPNST.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]