=====Cyst=====
A cyst is a closed sac, having a distinct [[membrane]] and division compared to the nearby [[tissue]]. Hence, it is a cluster of cells that have grouped together to form a sac (not unlike the manner in which water molecules group together, forming a bubble); however, the distinguishing aspect of a cyst is the cells forming the "shell" of such a sac, being distinctly abnormal (in both appearance and behaviour) when compared to all surrounding cells for that given location. It may contain air, fluids, or semi-solid material.

see [[Tumor cyst]].

===== Types =====

[[Intracranial cyst]]

[[Arachnoid cyst]].



[[Cystic tumor]]

[[Dermoid cyst]].

[[Epidermoid cyst]].

[[Neuroglial cyst]].

[[Pineal cyst]].

Cystic lesions in the [[atrium]] (trigone) of the lateral ventricle may become symptomatic due to obstruction of physiological CSF circulation and/or from mass effect on adjacent structures.
----

[[Synovial cyst]].

[[Tarlov cyst]]

[[Juxtafacet cyst]].
----