Does this entity require follow-up? In what situations is follow-up required?
Only if large (>10mm) or atypical imaging features.
What is the main differential diagnosis, which results in the need for followup?
Cystic pineal tumours e.g. pineocytoma.
Selected images from a contrast enhanced MRI demonstrate an incidental 12mm cystic lesion in the region of the pineal gland. The tectal plate is somewhat distorted (best seen on sagittal T1 image) but there is no evidence of obstructive hydrocephalus.
The cyst does not have any solid component and has fluid signal which does not however fully attenuate on FLAIR. There is no restricted diffusion on DWI/ADC.
On the coronal post gad image the internal cerebral veins can be seen elevated and splayed.