Cerebellar Astrocytoma

  • Etiology: Low grade astocytoma
  • Imaging:
    — Located in cerebellar hemisphere (50%) or cerebellar vermis (50%) and therefore lateral or posterior to fourth ventricle which is displaced or effaced
    — Large well circumscribed cyst with an enhancing mural nodule (80%)
    — Occasionally solid
    — 20% calcified
    — Wall may or may not enhance
  • DDX:
  • Complications:
  • Treatment: Surgical
  • Clinical: Pilocytic (80%) versus diffuse (20%)

Radiology Cases of Cerebellar Astrocytoma

CT of cerebellar astrocytoma
Axial CT with contrast of the brain shows a large heterogeneous cystic and solid mass encompassing the entire right cerebellar hemisphere which is compressing the slit-like fourth ventricle and shifting it to the left, resulting in obstructive hydrocephalus of the third and lateral ventricles.
CT and MRI of cerebellar astrocytoma
Axial CT without contrast of the brain (above left) shows a primarily cystic lesion in the left cerebellar hemisphere that has a solid component posteriorly that contains calcification. There is mild to moderate obstructive hydrocephalus present. Axial (above right) and coronal (below left) T1 MRI with contrast of the brain shows a primarily cystic lesion in the left cerebellar hemisphere that has a solid component posteriorly that enhances. There is mild to moderate hydrocephalus present. Sagittal T1 MRI with contrast (below right) shows the cerebellar mass causing tonsillar herniation beneath the foramen magnum.
CT and MRI of cerebellar astrocystoma
Axial CT without contrast of the brain (above) shows moderate dilation of the lateral, third and fourth ventricles. Axial T2 MRI without contrast of the brain (below left) shows a round focus of bright signal in the posterior medulla that on the sagittal T1 MRI post contrast (below right) shows it to be a non-enhancing mass in the floor of the fourth ventricle causing ventricular outlet obstruction.