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Low Grade Astrocytoma (LGA) Clinical Features


Juvenile pilocytic astrocytomas (JPA)

Most common pediatric low-grade astrocytoma

  • Peak incidence between 5-14 years:
    • Other low grade astrocytomas tend to have an older peak incidence (between 30-40 years)
    • Occur at a younger age than anaplastic astrocytomas, whose average age is 40-60 years
    • 25% of all cerebellar hemispheric astrocytomas
    • 60% of all optic gliomas

  • Most commonly located along the midline
    • Tend to develop in midline periventricular zones
  • Generally:
    • Discrete
    • Indolent
    • Associated with cyst formation

Common locations:


  • Cerebellum very commonly affected (80-85% of all JPAs arise in the cerebellum)
  • This site carries the most favorable prognosis
  • Tends to be well-circumscribed
  • Accessible for surgical resection


Supratentorial locations often involve:

  • Optic pathway
  • Hypothalamic area
  • Thalamus
  • Area around the 3rd ventricles
  • Tumors in the cerebral hemispheres tend to be located in medial temporal lobe.


The image below is an axial MR (post-gad T1) of a posterior fossa pilocytic astrocytoma. #1 points to the anterior cystic component and #2 points to the enhancing, solid posterior component.

Here is a sagittal veiw of the same tumor:


Below is a MR scan (coronal section) which shows a T2 hyperintense mass in the right temporal lobe (#1). This is a pilocytic astrocytoma.



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