Posterior fossa tumors

Medulloblastom
in der MRT
Wikipedia • CC BY-SA 3.0
Role of
diffusion-weighted imaging in differentiation between posterior fossa brain tumors. Juvenile pilocytic astrocytoma in a 9-year-old boy who presented with repeated headache and vomiting. a T1-weighted (T1WI) shows intra-axial cystic space-occupying lesion (SOL) in the left cerebellar hemisphere. b T2-weighted (T2WI) showing hyperintense cystic posterior fossa mass with isointense solid mural nodule attached to the inner side of the cystic mass. Note the cystic components and relatively solid components. c Post-contrast T1WI axial image showing mildly enhancing solid components and faint enhanced cystic wall. d Apparent diffusion coefficient (ADC) map: the cystic component is bright while the solid component is relatively lower than the cystic component with slight diffusion restriction
ejnpn.springeropen.com • CC-by-4.0
Role of
diffusion-weighted imaging in differentiation between posterior fossa brain tumors. Typical MRI features of a medulloblastoma in a 3-year-old child who presented with chronic headache 5 months ago. a T1WI shows midline vermian hypointense mass in the posterior fossa causing anterior displacement of the fourth ventricle. b T2WI: the mass appears isointense to slightly hyperintense. Few T1WI hypointense and T2WI hyperintense foci suggestive of cystic components. c Post-contrast T1WI axial image showing intense enhancement of the mass. d Low signal on apparent diffusion coefficient images (ADC), features suggestive of restricted diffusion corresponding to hypercellularity of the mass
ejnpn.springeropen.com • CC-by-4.0
Role of
diffusion-weighted imaging in differentiation between posterior fossa brain tumors. Typical cerebellar (infratentorial) meningioma in female patient aged 44 years old presented with chronic headache and dizziness 4 months ago. An extra-axial space-occupying lesion (SOL) is seen in the left cerebellar hemisphere lying below and contacting the tentorium cerebelli with moderate perifocal edema, effacement of related cerebellar folia, compression of the fourth ventricle, and minimal rightward shift of midline structures. This mass displays relatively iso to low signal intensity (SI) on T1WI (a), iso SI on T2 WI (b). It shows homogeneous enhancement on post-contrast T1WI (c). It has iso SI-like brain parenchyma on apparent diffusion coefficient images (ADC) map (d)
ejnpn.springeropen.com • CC-by-4.0
Role of
diffusion-weighted imaging in differentiation between posterior fossa brain tumors. Epidermoid cyst in 38-year-old male complaining from auditory problems. A lobulated extra-axial cystic lesion is seen in the right cerebellopontine angle (CPA) insinuating itself, compressing the pons, extending into prepontine cistern, and encasing the basilar artery. It displays low T1WI signal intensity (a) and high T2WI signal intensity cerebrospinal fluid (CSF) like (b). On FLAIR, it shows low SI (partially suppressed SI (c). It shows faint marginal enhancement on post-contrast study (d). It shows iso SI-like brain parenchyma (restricted diffusion); it does not have high CSF SI-like arachnoid cyst (e)
ejnpn.springeropen.com • CC-by-4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Posterior fossa tumor has a very different differential in an adult as opposed to a child.

Adult

An important space-occupying lesion (the most common in fact) to remember is that of a stroke, which when subacute can mimic a tumor.

Child

A quick and handy mnemonic for posterior fossa tumors in children is BEAM.

Although it is true that posterior fossa tumors are much more common in children than in adults the distribution does vary with age :

  • 0 to 3 years of age: supratentorial > infratentorial
  • 4 to 10 years of age: infratentorial > supratentorial
  • 10 to early adulthood: infratentorial = supratentorial
  • adults: supratentorial > infratentorial

Overall 50-55% of all brain tumors in children are found in the posterior fossa .

Siehe auch:
und weiter: