title: Primary intracranial Ewing's sarcoma with unusual features.
abstract: Pediatric primary "small round blue cell" tumors in the CNS represent several entities, some more common than others. Ewing sarcoma/peripheral primitive neuroectodermal tumor (ES/pPNET) is rare and must be distinguished from other tumors such as medulloblastoma [1, 2], atypical rhabdoid/teratoid tumor, ependymomal tumors, metastatic sarcomas, hematologic malignancies, and other mimics. Although therapy for ES/pPNET is effective, it brings severe side effects, including cardiac toxicity, making correct recognition important [3]. As small blue cell tumors look similar, diagnosis often depends on special stains, immunohistochemistry, and molecular techniques. While the combination of membranous immunohistochemical reactivity for CD99 with cytoplasmic glycogen provides effective screening, demonstration of characteristic translocations of EWSR1 (chromosome 22) or FUS (chromosome 16) by fluorescent in situ hybridization (FISH) can confirm the diagnosis. We are reporting three primary ES/pPNET of the CNS, two of which occurred in children. While the adult case demonstrates the classic histopathology, the two pediatric cases have histopathology that significantly deviates from the usual. One is suggestive of a primary sarcoma, and the other mimics an ependymoma, but all three cases are confirmed with FISH. These observations suggest that primary ES in the CNS may have histology different from the classic morphology and a high index of suspicion should be maintained in order to make the correct diagnosis. A search of the literature suggests that these tumors are most frequently seen in children and young adults. Imaging often shows a supratentorial enhancing mass that touches the leptomeninges. Survival over three years is good but long term prognosis is unknown [3, 4].
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center Oklahoma City, OK 73104, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: VandenHeuvel
authors.affiliation: Department of Pathology and Laboratory Medicine, Albany Medical College Albany, NY 12208, USA.
authors.forename: Rami N
authors.initials: RN
authors.lastname: Al-Rohil
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center Oklahoma City, OK 73104, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Stevenson
authors.affiliation: Department of Pathology and Laboratory Medicine, Albany Medical College Albany, NY 12208, USA.
authors.forename: Jiang
authors.initials: J
authors.lastname: Qian
authors.affiliation: Department of Neurosurgery, University of Oklahoma Health Sciences Center Oklahoma City, OK 73104, USA.
authors.forename: Naina L
authors.initials: NL
authors.lastname: Gross
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center Oklahoma City, OK 73104, USA.
authors.forename: Rene
authors.initials: R
authors.lastname: McNall-Knapp
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center Oklahoma City, OK 73104, USA.
authors.forename: Shibo
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Pathology, Children's Hospital of Colorado CO, USA.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Wartchow
authors.affiliation: Department of Pathology, Children's Hospital of Colorado CO, USA.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Mierau
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center Oklahoma City, OK 73104, USA ; Department of Pathology, Oklahoma City Veterans Administration Medical Center Oklahoma City, OK 73104, USA.
authors.forename: Kar-Ming
authors.initials: KM
authors.lastname: Fung
mesh_terms: D001932:Brain Neoplasms / Q000473:pathology*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D018242:Neuroectodermal Tumors, Primitive / Q000473:pathology*; D012512:Sarcoma, Ewing / Q000473:pathology*
keywords: Ewing sarcoma; diagnosis; peripheral primitive neuroectodermal tumor