A 15-year-old boy complains of right-sided weakness and gait impairment. A CT scan shows a large, non-enhancing cyst in the posterior cranial fossa, with an enhancing tumor nodule in the left cerebellum. What is the most likely diagnosis?
An arachnoid cyst
A cystic astrocytoma
Rathke's cleft cyst
Glioblastoma multiforme
Cystic astrocytoma's are neoplasms of the CNS. They usually consist of a large, non-enhancing cyst on the wall of which is an enhancing tumor nodule. They are most commonly found within the substance of the cerebellar hemispheres of children and young adults. A Rathke's cleft cyst is a remnant of the embryologic Rathke's pouch. These are found within the sella turcica.
Nervous System