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[edit] Discussion

  • Medulloblastoma is a highly malignant neuroepithelial tumor of the posterior fossa
  • Predominantly seen in children
  • Medulloblastoma is the most common malignant central nervous system tumor in children and the second most common pediatric brain neoplasm, following only juvenile pilocytic astrocytoma.
  • It accounts for up to 38% of all pediatric posterior fossa tumors and represents the most common pediatric posterior fossa tumor overall.
  • The cerebellum is the most common location for medulloblastomas (approx 94.4% of cases), and most (>75%) of these arise in the midline cerebellar vermis.
  • More lateral locations within the cerebellar hemisphere are typical when these tumors manifest in older children, adolescents, and adults.
  • Subarachnoid seeding is common in medulloblastomas, occurring in up to 33% of all patients at the time of initial diagnosis.
  • 5-year survival rates is between 50% and 70% in most studies.
  • Typical clinical histories are usually brief and reflect the aggressive biologic behavior of the tumor.
  • Most (75%) patients have symptoms for less than 3 months.

  • Therapy: Surgical resection and reestablishment of normal CSF flow remain the cornerstones of treatment of medulloblastoma in virtually all cases.
  • Medullblastomas are very radiosensitive and the combination of surgery and radiation therapy is commonly used
  • The use of either preoperative or postoperative chemotherapy is associated with an increase in survival rates in high-risk children with medulloblastoma (ie, those with fourth ventricle invasion and children less than 2 years of age).

[edit] Imaging Findings

[edit] CT

  • Classic appearance of a medulloblastoma is a hyperattenuated, well-defined vermian cerebellar mass with surrounding vasogenic edema, evidence of hydrocephalus, and homogeneous enhancement on contrast material–enhanced images in a child less than 10 years of age.

[edit] MRI

  • Typical appearance of a medulloblastoma is iso- to- hypointense relative to white matter with T1 weighted images and variable signal intensity relative to white matter t2 weighted images.
  • Nearly all enhance following the intravenous administration of contrast material, but the enhancement is usually heterogeneous.

[edit] Differential Diagnosis

  • Most likely alternative consideration for a hyperattenuated midline cerebellar mass in a child is an ependymoma.
  • In contrast to a medulloblastoma, an ependymoma is typically calcified and often extends from its common fourth ventricular origin through the foramen of Luschka into the adjacent cerebellopontine cistern.

[edit] Images

Patient #1

Patient #2

[edit] See Also

[edit] External Links

[edit] References