Non-Rathke Cleft Cysts

Apart from Rathke cleft cysts, many cyst-like T2W hyperintense images can be seen in the sella. Some may correspond to focal area of necrosis, mininfarcts, or hemorrhagic scars. Others can be specifically characterized as arachnoid cysts. Cystic lesions are also found at the most posterior part of the sella, against the dorsum sellae. They are located on the midline and demonstrate a T2W hyperintense signal and a T1W hypointense one. Above all, these cysts are totally surrounded by a T1W hyperintense ring representing the vasopressin stored in the posterior lobe pushed aside by the cyst. This cyst which size varies from a few millimeters to 10 mm then presents as a posterior lobe cyst. Nevertheless, it has to be noted that these cysts are not reported in the pathologic literature. Other cyst-like lesions are found above the posterior lobe and can mimic an extension of the CSF spaces below the sellar diaphragm. They can display a high signal on FLAIR. Non-Rathke cysts can be proposed to name them.