Extraosseous Ewing's sarcoma/peripheral neuroectodermal tumors (ES/PNETs) are rare neoplasms that account for approximately 10%-15% of soft tissue sarcomas in children and 5% of soft tissue sarcomas in adults. Primary spinal, extraosseous, intradural ES/PNETs are even less common. The diagnosis of ES/PNET is extremely challenging, because the tumor can have a nonspecific radiologic appearance, and the histologic features are shared by many other "small round cell tumors." Thus, ES/PNET should be included in the radiologic and pathologic differential diagnosis, even in older patients and in unusual tumor sites. We report two cases of spinal, extraosseous, intradural ES/PNETs in adults who presented with back pain. Magnetic resonance imaging revealed contrast enhancing, intradural lesions in the area of the conus medullaris. The tumor in Case 1 was partially intramedullary, while the tumor in Case 2 was exclusively extramedullary. In both cases, the radiologic and intraoperative surgical impression favored ependymoma. The diagnosis of ES/PNET was established in both cases by histopathologic, immunohistochemical, and molecular analysis.
Mardekian, Stacey K.; Gandhe, MD, Ashish; Miettinen, Markku; Pack, Svetlana; Curtis, Mark T. MD, PhD; and Abdullaev, Ziedulla, "Two Cases of Spinal, Extraosseous, Intradural Ewing's sarcoma/Peripheral Neuroectodermal Tumor: Radiologic, Pathologic, and Molecular Analysis." (2014). Department of Radiology Faculty Papers. Paper 36.