17mm pineal cyst found on mri, going to be discussed in mdt meeting. how worried should i be?

Depends on symptoms: Kayleigh, Pineal cysts are generally benign and seen quite frequently in folks who have nothing wrong with their brain. Once they get above 5 mm, they have the possibility of causing symptoms such as headache, seizure, or light sensitivity. Nowadays if too large, they are drained through endoscopic brain surgery which requires only one night hospital stay and is relatively painless.