title: What's in a name? Intracranial peripheral primitive neuroectodermal tumors and CNS primitive neuroectodermal tumors are not the same.
abstract: BACKGROUND
  Intracranial peripheral primitive neuroectodermal tumors (P-PNET) are extremely rare. They can be easily misdiagnosed as central nervous system primitive neuroectodermal tumors (CNS-PNET) or meningiomas. Little is known about the optimal treatment and prognosis of these tumors.
  
  
  METHODS
  We evaluated the treatment and outcome of 17 patients with intracranial, nonmetastatic, genetically confirmed P-PNET. Three patients were treated at our institutions. Thirteen other cases providing sufficient treatment and follow-up information were extracted from the literature.
  
  
  RESULTS
  The median age at diagnosis was 17 years. All patients underwent initial surgery. Complete resection was achieved in 9 of the 17 cases (53 %). Combined adjuvant treatment consisting of radiotherapy (focal, n = 10; craniospinal, n = 1) and chemotherapy was administered to 11 of the 17 patients (59 %). The median follow-up time was 1.4 years. In 8 of the 17 patients (47 %), the disease progressed; 4 of the 17 patients (24 %) died. The 2-year progression-free and overall survival rates were 64 % and 76 %, respectively.
  
  
  CONCLUSIONS
  The differential diagnosis for intracranial, meningeal-based, small, round-cell tumors should include P-PNET. It is highly probable that complete resection has a positive impact on survival--as previously reported for extracranial P-PNET--but this cannot be shown by our data. Intensive adjuvant treatment consisting of radiotherapy and chemotherapy seems to be essential. A statistically grounded recommendation for the appropriate target volume and radiation dose is not yet possible. However, in most case reports of primary intracranial P-PNET published to date, patients were treated with focal irradiation. The optimal chemotherapy regimen has yet to be established, with both the Ewing tumor and CNS-PNET protocols being promising candidates for effective treatment.
authors.affiliation: Department of Radiotherapy and Radio-Oncology, University of Leipzig, Stephanstr. 9a, 04103, Leipzig, Germany. Klaus.Mueller@medizin.uni-leipzig.de
authors.forename: K
authors.initials: K
authors.lastname: Müller
authors.forename: B
authors.initials: B
authors.lastname: Diez
authors.forename: A
authors.initials: A
authors.lastname: Muggeri
authors.forename: T
authors.initials: T
authors.lastname: Pietsch
authors.forename: C
authors.initials: C
authors.lastname: Friedrich
authors.forename: S
authors.initials: S
authors.lastname: Rutkowski
authors.forename: K
authors.initials: K
authors.lastname: von Hoff
authors.forename: A O
authors.initials: AO
authors.lastname: von Bueren
authors.forename: I
authors.initials: I
authors.lastname: Zwiener
authors.forename: F
authors.initials: F
authors.lastname: Bruns
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000175:diagnosis / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000175:diagnosis / Q000532:radiotherapy*; D012189:Retrospective Studies; D009626:Terminology as Topic; D016896:Treatment Outcome; D055815:Young Adult