title: Pediatric cerebellar pilomyxoid-spectrum astrocytomas.
abstract: OBJECTIVE
  Pediatric cerebellar astrocytomas with pilomyxoid features include classic pilomyxoid astrocytomas (PMAs) and intermediate pilomyxoid tumors (IPTs). Since the original description of PMA in 1999, most reports in the literature have described PMAs arising from the hypothalamic/chiasmatic region. To the authors' knowledge, PMAs arising from the posterior fossa have not been discussed in the neurosurgical literature. Intermediate pilomyxoid tumors, or tumors with pathological features of both pilocytic astrocytoma (PA) and PMA, have only recently been described. In this article, the authors present 2 cases that fall within the spectrum of pediatric cerebellar PMA-including a classic PMA and an intermediate pilomyxoid tumor. The authors compare the radiological presentation, surgical results, and postoperative course to findings in a cohort of 15 patients with cerebellar PAs.
  
  
  METHODS
  Between 2003 and 2010, 2 patients with pilomyxoid-spectrum astrocytomas underwent treatment at Vanderbilt Children's Hospital. One was a 22-month-old girl who presented with progressive gait disturbance and falls. The other was a 4-year-old girl who presented with ataxia and generalized weakness. In a retrospective review of pediatric cerebellar neoplasms resected by the senior author during this period, these tumors comprised 4% of cerebellar neoplasms and approximately 10% of cerebellar glial neoplasms.
  
  
  RESULTS
  Both patients were treated with midline suboccipital craniotomy for resection. In both cases, tumor invasion anteriorly into the brainstem prevented gross-total resection. the patient in Case 1 was placed on chemotherapy following pathological diagnosis and later developed definitive evidence of leptomeningeal dissemination (LD) 3 years after the operation. The patient in Case 2 was placed on chemotherapy after exhibiting progressive evidence of local recurrence (findings were negative for LD) 12 months following resection.
  
  
  CONCLUSIONS
  Pediatric patients with cerebellar pilomyxoid-spectrum astrocytomas appear to suffer higher rates of local recurrence and LD than pediatric patients with cerebellar PAs.
authors: Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA. jonathan.forbes@vanderbilt.edu
authors: Jonathan A
authors: JA
authors: Forbes
authors: Bret C
authors: BC
authors: Mobley
authors: Thomas M
authors: TM
authors: O'Lynnger
authors: Calvin M
authors: CM
authors: Cooper
authors: Mahan
authors: M
authors: Ghiassi
authors: Rimal
authors: R
authors: Hanif
authors: Matthew M
authors: MM
authors: Pearson
mesh_terms: D001254:Astrocytoma / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000601:surgery*; D002528:Cerebellar Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000601:surgery*; D002531:Cerebellum / Q000473:pathology / Q000601:surgery; D002551:Cerebral Ventricle Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000601:surgery*; D017024:Chemotherapy, Adjuvant; D002675:Child, Preschool; D003131:Combined Modality Therapy; D003388:Cranial Fossa, Posterior / Q000473:pathology / Q000601:surgery*; D003399:Craniotomy / Q000379:methods; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D004210:Dissection / Q000379:methods; D005260:Female; D020546:Fourth Ventricle / Q000473:pathology / Q000601:surgery; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008578:Meninges / Q000473:pathology; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D009460:Neurologic Examination; D019292:Skull Base Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000601:surgery*