What sequence would you look at to confirm that this does not represent an epidermoid cyst?
Diffusion weighted imaging would demonstrate high signal (diffusion restriction) in an epidermoid cyst.
What is the most common location for arachnoid cysts?
Most frequently (50-60%) arachnoid cysts are located in the middle cranial fossa, where they invaginate into the Sylvian fissure and and widen it.
A supracerebellar CSF intensity cyst measuring 33 x 34 x 29 mm produces mass effect on the cerebellum and elevates the tentorium cerebelli and displaces the pineal gland a little superiorly and anteriorly. It is slightly eccentric to the right, resulting in slightly greater inferior cerebellar tonsillar herniation on the right (6 mm) than on the left (3 mm). The tectum is not significantly compressed and no hydrocephalus is present.