title: Differential imaging characteristics and dissemination potential of pilomyxoid astrocytomas versus pilocytic astrocytomas.
abstract: BACKGROUND
  Pilomyxoid astrocytoma (PMA) is a rare WHO grade II tumor occurring most often in young children. PMA is associated with worse outcome as compared to the pathologically related pilocytic astrocytoma (PA). The radiological differentiation of PMAs from PAs is challenging. Furthermore, it is not completely clarified whether PMA is associated with a higher rate of cerebrospinal fluid (CSF) dissemination in the youngest pediatric population as compared to PA. The aim of our study was firstly to compare imaging features of these tumors and, secondly, to evaluate the occurrence of CSF dissemination.
  
  
  METHODS
  The study population included 15 children with PMA and 32 children with PA. The initial MRI and CT scans from the time of the diagnosis were retrospectively analyzed according to standardized criteria and the findings compared between the two tumor types. Furthermore, we also compared the occurrence of imaging evidences of CSF dissemination.
  
  
  RESULTS
  PMAs showed less frequently cystic components (p = 0.03) and never had large tumor cysts. Gadolinium enhancement of PMAs was more frequently homogeneous (p = 0.006). PMAs appeared to show more often intratumoral hemorrhages (p = 0.047). Within the subgroup of children <6 years of age, the PMA histology tended to have a larger effect on the occurrence of CSF dissemination than the age (p = 0.05 vs. 0.12).
  
  
  CONCLUSIONS
  Some imaging features like enhancement pattern or presence of cysts or hemorrhage may help differentiating these low-grade gliomas. Our results confirm previous scarce data suggesting a higher rate of CSF dissemination in PMAs, even in the youngest patient population.
authors: Department of Neuroradiology, Universitätsklinikum Würzburg, Josef-Schneider-Strasse 11, 97080, Würzburg, Germany, Alkonyi_B@ukw.de.
authors: Bálint
authors: B
authors: Alkonyi
authors: Johannes
authors: J
authors: Nowak
authors: Astrid K
authors: AK
authors: Gnekow
authors: Torsten
authors: T
authors: Pietsch
authors: Monika
authors: M
authors: Warmuth-Metz
mesh_terms: D000367:Age Factors; D001254:Astrocytoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media