Presentation
Headache, ataxia
Patient Data
Large extra-axial cystic space occupying lesion in left retrocerebellar, extending from posterior fossa to vertex, appears hypointense in T1W and hyperintense in T2Wimages, exhibits CSF signal intensity in FLAIR sequences. It shows no restricted diffusion in DW/ADC sequences.
It causes mass effect in form of severe compression and buckling of left cerebellar hemisphere, subsequently compressing IVth ventricle and slightly cerebellar coning into foramen magnum, indenting medulla oblongata, compressing torcula, straight sinus and posterior part of superior sagittal sinus (preserved T2-signal void appearance).
Case Discussion
Large extra-axial cystic space occupying lesion extending from posterior fossa to vertex, of CSF signal intensity, not restricted diffusion, causes mass effect, suggestive large arachnoid cyst.