- 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).
 Imaging Findings
- 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.
- 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.
 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.
 See Also
 External Links
- Kelly K. Koeller, and Elisabeth J. Rushing. From the Archives of the AFIP: Medulloblastoma: A Comprehensive Review with Radiologic-Pathologic Correlation. RadioGraphics 2003 23: 1613-1637.