====== Mega cisterna magna differential diagnosis ======

[[Mega cisterna magna]] needs to be distinguished from other causes of an enlarged retrocerebellar CSF space:

[[Posterior fossa arachnoid cyst]]
    
[[Epidermoid cyst]]: often shows a heterogeneous/dirty signal on FLAIR and restricted diffusion
    
[[Cerebellar vermis hypoplasia]]
    
[[Dandy Walker malformation]]: vermis not intact
    
[[Blake's pouch cyst]]: usually a hydrocephalus is present 
    
[[Pilocytic astrocytoma]]: if very posterior and predominantly cystic.