|T1 post-gad||T1 post-gad||T2|
Pathologically they arise from rests of squamous tissue in Rathke's cleft. Grossly they are usually well defined cystic mass often with a mural nodule. The cyst may contain fluid which ranges in color from light to very dark viscous material resembling crank case oil. This fluid is usually rich in cholesterol crystals. 90% are calcified. The contents of the cyst are usually slightly higher in attenuation when compared to CSF on CT.
They demonstrate heterogeneous enhancement and signal characteristics on MR often with a nodular or rim like enhancement. An enhancing mural nodule is typical. The differential for this case is somewhat limited due to the characteristic appearance. Metastasis is a much less likely possibility but may be considered given the age of the patient. Astrocytoma would be highly unusual since this lesion occupies the third ventricle and the suprasellar region. Rathke cleft cysts do occur here; however, they typically appear as an isolated cystic lesion with rim enhancement without nodularity. Furthermore, Rathke cleft cysts occur in a younger age group and are rarely completely suprasellar. 3/4 of Rathke cleft cysts have both intra and suprasellar components . Pituitary adenoma is not in the differential in this case since there is no sellar component. Related Cases
|Pituitary adenoma||Choroid plexus papilloma||ACA aneurysm|