Male, 10 years old, with autism and concern for epilepsy. A cystic lesion is evident along the superior aspect of the mid left hippocampal body which follows CSF signal on all sequences. This lesion exerts some degree of mass effect upon the underlying hippocampus which is slightly flattened as a result. The lesion does not appear to arise from the hippocampus, but instead may be intraventricular in origin, possibly related to the choroid plexus.Brain parenchymal morphology is otherwise within normal limits. No evidence of edema or mass effect is seen. No structural abnormalities or evidence of dysplasia or migrational abnormality are noted. There is no significant parenchymal edema. No evidence of intracranial hemorrhage is seen. The ventricles are unremarkable. The mesial temporal lobes are otherwise unremarkable.
A cystic lesion is evident centered along the superior aspect of the mid left hippocampal body. This lesion is too far posterior to represent a choroidal fissure cyst, and the location and orientation are not appropriate for a hippocampal sulcus remnant cyst. Instead, it appears that the lesion may be intraventricular in origin, possibly representing an arachnoid cyst or a choroid plexus cyst.