====== Suprasellar arachnoid cyst classification ======
In 2016 André proposed

SAC-1 may come from an expansion of the diencephalic leaf of the Liliequist membrane. 

SAC-2 show a dilatation of the interpeduncular cistern and correspond to a defect of the mesencephalic leaf of the Liliequist membrane. 

SAC-3 correspond to the asymmetrical forms expanding to other subarachnoid spaces. Surgical treatment is not always necessary. The recognition of the different subtypes will allow choosing the best treatment option
((André A, Zérah M, Roujeau T, Brunelle F, Blauwblomme T, Puget S, Bourgeois M, 
Sainte-Rose C, Ville Y, Di Rocco F. Suprasellar Arachnoid Cysts: Toward a New
Simple Classification Based on Prognosis and Treatment Modality. Neurosurgery.
2016 Mar;78(3):370-9; discussion 379-80. doi: 10.1227/NEU.0000000000001049.
PubMed PMID: 26445374.
))
----


A suprasellar cyst can be a communicating cyst with a valve at the penetration of the [[basilar artery]] (BA) through the prepontine arachnoid membrane or be a noncommunicating cyst 
((Pierre-Kahn A, Capelle L, Brauner R, Sainte-Rose C, Renier D, Rappaport R, Hirsch JF: Presentation and management of suprasellar arachnoid cysts. Review of 20 cases. J Neurosurg 1990, 73:355-9.)).

Miyajima et al proposed a classification:

1) a noncommunicating intra-arachnoid cyst of the diencephalic [[Liliequist membrane]] 

2) a communicating cyst that is a cystic dilation of the [[interpeduncular cistern]]
((Miyajima M, Arai H, Okuda O, Hishii M, Nakanishi H, Sato K: Possible origin
of suprasellar arachnoid cysts: neuroimaging and neurosurgical observations in nine cases. J Neurosurg 2000, 93:62-7.)).