Pediatric Cerebellar Tumors

Case A: A right medullary/cerebellar heterogeneous T2 enhancing lesion is seen with a large cystic component. There are no associated ADC abnormalities.

Case B: A noncontrast CT scan demonstrates a well-defined posterior fossa lesion with solid and cystic components. MRI shows that the lesion is centered in the superior vermis and demonstrates intense enhancement of the solid component and rim enhancement of the wall of the cystic component.

Case C: Axial MRI demonstrates well-defined lesion with central T2 prolongation and a rim of T2 shortening. On a postgadolinium image, the tumor extends up to the dural surface and a branch of the anterior inferior cerebellar artery enters the anterior surface of the avidly enhancing lesion. On a T2 gradient refocused echo image ( D ), a rim of susceptibility suggests a hemorrhagic component.

Case D: A well-defined lesion noted in the superior cerebellum demonstrates a fluid-fluid level and rim enhancement. The blood fluid level represents hemorrhage within the cystic component. In addition, the large nonenhancing T1 and T2 hypointensity anterior to blood fluid level likely represents an older hemorrhagic component.

Case E: A large left cerebellar lesion is seen extending from the fourth ventricular margin to the pial surface. The lesion demonstrates heterogenous enhancement predominantly in the subpial region. Areas of low diffusivity, vasogenic edema, and the mass effect on the fourth ventricle are seen, along with associated hydrocephalus (note the dilated temporal horns).