Malignant Peripheral Nerve Sheath Tumors Masking as Ewing Sarcoma/Primitive Neuroectodermal Tumors.

Shaikh Shaikh

doi:10.4021/wjon661w

Abstract

Malignant peripheral nerve tumors, a small subset of soft tissue sarcomas, provide a unique diagnostic challenge. Although they may arise from peripheral nerves or from cells associated with nerve sheaths, malignant peripheral nerve tumors often present with diverse immunohistochemical features similar to those of other tumors. These features make MPNSTs difficult to diagnose and classify. We present a case of a 26-year-old female presenting with a rapidly growing soft tissue mass. The mass was excised and immunohistological staining suggested a Ewing’s sarcoma/Primitive neuroectodermal tumor. Confirmational studies did not confirm this diagnosis and upon further review, the diagnosis was changed to a malignant peripheral nerve sheath tumor. We reviewed this case in the setting of the reported literature concerning MPNSTs with focus on the epidemiologic, diagnostic, and immunohistologic features that distinguish this tumor from other similar malignancies.

Highlights

Malignant peripheral nerve sheath tumors (MPNST) comprise a small subset of only 5-10% of soft tissue sarcomas [1, 2]
A small subset of soft tissue sarcomas, provide a unique diagnostic challenge. They may arise from peripheral nerves or from cells associated with nerve sheaths, malignant peripheral nerve tumors often present with diverse immunohistochemical features similar to those of other tumors
Confirmational studies did not confirm this diagnosis and upon further review, the diagnosis was changed to a malignant peripheral nerve sheath tumor

Summary

Introduction

Malignant peripheral nerve sheath tumors (MPNST) comprise a small subset of only 5-10% of soft tissue sarcomas [1, 2]. The histological presentations of MPNST vary greatly and provide a unique diagnostic challenge Per our review, they are only a handful of reports showing MPNSTs with areas of primitive neuroepithelial differentiation. The mass protruded through the skin, was very tender to palpation, and expressed multiple areas of hemorrhage It spanned about five centimeters in diameter along the left lateral aspect of a transverse C-section incision (Fig. 1). The patient subsequently completed two cycles of chemotherapy with cyclophosphamide, doxorubicin and vincristine alternating with ifosfamide and etoposide By this time, the confirmatory genetic studies returned negative, questioning the original diagnosis. The biopsy specimen had a shiny appearance suggesting myxoidal features along with other areas of hemorrhage (Fig. 4). On histopathological examination (Fig. 5, 6), the specimen again revealed myxoidal features with small round blue cells and other areas of spindle. It stained negatively for CD31, CD34, desmin, melan-A, SMA, pankeratin, EMA, CD45, CD56, chromogranin, and synaptophysin

Discussion

Findings

Conclusion