Sagittal view of an MRI scan (with contrast) of brain from a 3 y/o male. There is a large cystic mass with a brightly enhancing mural nodule in the cerebellum. The location of the tumor, its appearance, and the patient age together are diagnostic of pilocytic astrocytoma. Case produced with permission, courtesy of Dr. Frank Gaillard. Radiopaedia. Complete case is here.