[Intrasellar arachnoid cysts: computed tomography and MRI. Apropos of 2 cases]

We describe the computed tomographic and magnetic resonance imaging findings in two cases of intrasellar arachnoid cysts. The diagnosis of intrasellar arachnoid cyst with suprasellar extension should be evoked in case of a cyst-like formation whose density and signal appear to be identical to those of the cerebrospinal fluid even if contrast uptake is evidenced in the cyst wall. Contrast uptake can be related to compression of the pituitary stalk and normal pituitary displacement. Suspected intrasellar arachnoid cyst modifies the surgical approach which must be made via a subfrontal route. We discuss the differential diagnosis with other intrasellar cystic formations such as necrosed tumor, abscesses, Rathke pouch cysts, cystic craniopharyngiomas, epidermoid cysts and parasite cysts.