Malignant peripheral nerve sheath tumors (MPNSTs) are defined as malignant tumors arising from peripheral nerves or differentiating along the line of the elements of the nerve sheath. MPNSTs that originate from the brain parenchyma are exceptionally rare and are termed malignant intracerebral nerve sheath tumors. We experienced a case of the epithelioid variant of malignant intracerebral nerve sheath tumor (MINST) occurring in the right frontal lobe of a 50-year-old man. He underwent gross total resection of the tumor. Histologically, the tumor cells had round, polygonal, or ovoid nuclei and moderate amounts of eosinophilic cytoplasm, which was defined as epithelioid cells. The tumor cells were arranged in short cords or nests with vaguely nodular patterns embedded in the myxoid stroma. Regarding mitotic activity, 15 mitotic figures were noted per 10 high-power fields. Immunohistochemically, tumor cells were positive for S-100 protein and synaptophysin, but negative for glial fibrillary acidic protein, HMB-45, EMA, and AE1/ AE3. Furthermore, immunostaining for INI1 was negative. Loss of the tumor-suppressor gene product SMARCB1/ INI1 expression has been recognized in epithelioid MPNST, but not in conventional MPNST. Postoperatively, he underwent radiotherapy and was followed for almost 1 year without recurrence. The present case is the first report of the epithelioid MINST.

Introduction
 Case report
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 References

• Seung-Myoung Son(Departments of Pathology, College of Medicine, Chungbuk National University, Cheongju 28644, Korea)
• Young Seok Park(Departments of Neurosurgery, College of Medicine, Chungbuk National University, Cheongju 28644, Korea)
• Ok-Jun Lee(Departments of Pathology, College of Medicine, Chungbuk National University, Cheongju 28644, Korea)