Primary intracranial dural-based Ewing sarcoma/peripheral primitive neuroectodermal tumor mimicking a meningioma: A rare tumor with review of literature

Abstract

Ewing sarcoma/peripheral primitive neuroectodermal tumor (ES/pPNET) is a malignant small, round cell tumor arising from bone and soft tissue in children and young adults. It can occur at osseous and extraosseous sites. Its usual locations are diaphysis of long bones followed by pelvis, ribs, vertebrae, and rarely skull. We reviewed the literature and PubMed advanced search on ES/pPNET occurring at extraosseous sites, mainly involving the central nervous system (CNS). We reported a case of a 22-year-old male presenting with seizure finally diagnosed as a case of ES/pPNET. The challenges in management of this rare CNS tumor and its differential diagnosis are highlighted. We found that most cases of ES involving CNS represent secondary metastases from extracranial sites of ES/pPNET and there are rare case reports of primary intracranial ES-pPNET. Furthermore, among these intracranial tumors, most common tumors occupy an intraaxial location and only a handful of cases of dural-based or extraaxial tumors mimicking meningioma are reported. Differentiation of pPNET from central PNET (cPNET) is important as it has definitive therapeutic and prognostic implications. Awareness of this entity of ES/pPNET, its rare dural presentation, and differentiation from the more common cPNET is needed for appropriate patient management. Meningeal ES/pPNET has to be kept in mind in the differential diagnosis of meningeal tumors eroding bone.

Keywords: Central nervous system Ewing sarcoma/peripheral primitive neuroectodermal tumor; Ewing's sarcoma; dural tumor; intracranial primitive neuroectodermal tumor; meningioma; peripheral primitive neuroectodermal tumor; primary.

Figure 1

Axial CECT showing a relatively well-defined dural-based tumor showing contrast enhancement

Figure 2

Photomicrograph showing a richly vascular small round cell tumor adjacent the dura (H and E, ×100)

Figure 3

Photomicrograph showing tumor composed of sheets of uniform small round cells with scant cytoplasm an area of necrosis and several mitotic figures (H and E, ×200)

Figure 4

Photomicrograph showing the small round cells adjacent to the overlying bone (H and E, ×200)

Figure 5

Tumor cells showing membranous expression of CD99 immunohistochemistry (×200)