title: Imaging characteristics of pilomyxoid astrocytomas in comparison with pilocytic astrocytomas.
abstract: OBJECTIVE
  Pilomyxoid astrocytoma (PMA) is a recently described astrocytic tumor that has been previously diagnosed as pilocytic astrocytoma (PA). The purpose of this study was to describe the imaging features of PMAs in comparison with PAs.
  
  
  METHODS
  We retrospectively reviewed CT/MR images and medical records of 10 patients with PMA and 38 patients with PA. The mean ages of patients with PMA and PA were 10 and 15 years, respectively. Imaging features including location, composition, enhancement pattern, presence of calcification, hemorrhage, and leptomeningeal dissemination were compared in patients with two tumor types.
  
  
  RESULTS
  Six PMAs (60%) occurred at the suprasellar area and the cerebellum was the most common (45%) site of PA. Solid component was dominant in eight PMAs (80%) and in 19 PAs (50%). All of the PMAs containing solid mass (n=8) included non-enhancing portion while 12/37 (32%) PAs included non-enhancing solid portion (p<0.05). Leptomeningeal dissemination was noted in five PMAs (50%) and one PA (3%) (p<0.05). Other imaging findings were not significantly different.
  
  
  CONCLUSIONS
  A younger age, more frequent occurrence at the suprasellar area, mainly solid mass containing non-enhancing portion, and more frequent leptomeningeal dissemination are helpful differential features of PMAs as compared to PAs.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710, Republic of Korea. leeinho1974@hanmail.net
authors.forename: In Ho
authors.initials: IH
authors.lastname: Lee
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Kim
authors.forename: Yeon-Lim
authors.initials: YL
authors.lastname: Suh
authors.forename: Hong
authors.initials: H
authors.lastname: Eo
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Shin
authors.forename: So-Young
authors.initials: SY
authors.lastname: Yoo
authors.forename: Kyung Soo
authors.initials: KS
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D001254:Astrocytoma / Q000000981:diagnostic imaging / Q000473:pathology*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D002531:Cerebellum / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008578:Meninges / Q000473:pathology; D009232:Myxoma / Q000000981:diagnostic imaging / Q000473:pathology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods