MRI of hemorrhagic choroid plexus cyst.

An unusual case of hemorrhage within a cyst in the choroid plexus of the lateral ventricle is presented. Choroid plexus cysts are commonly found incidentally on imaging studies, particularly MRI, where their characteristic appearance produces little diagnostic difficulty. In this case, high signal intensity of the cyst contents on T1-weighted images and apparent hemosiderin deposition in the cyst wall, not previously described, represented a dramatic change from a study 10 weeks previously and allowed a presumptive diagnosis of hemorrhage into the cyst, a presumption further supported by the changes in signal 20 weeks later.