Title: A Different kettle of fish:  An interesting case of giant aneurysm initially diagnosed as pituitary adenoma.

P C Valsalakumari, N Damani, T Galliford, West Hertfordshire NHS Trust.


Aneurysms of the sella region are commonly mistaken for pituitary adenomas, since they can have similar clinical, endocrinological and neurological symptoms.  Mass like features of giant aneurysms and compression to adjacent cranial nerves or cerebrum can produce clinical and neurological presentation of space occupying lesion. There is a reported case in which a patient underwent transphenoidal exploration based on CT findings where prominent intracavernous veins were found, inconsistent with pituitary adenoma. We report a case of basilar artery aneurysm intitally thought to be a pituitary mass on CT but subsequently diagnosed as a megabasilar artery on MRI.


Case history:

68 year old gentleman presented with a 2 day history of intermittent confusion and right sided headache. His past medical history is significant for type 2 diabetes, hypertension and a previous CVA with residual mild left hemiparesis.  On examination he was found to have an AMTS of 8/10 and had a left homonymous hemianopia. The remaining system examination was unremarkable and old left hemiparesis was noted.

Investigations and treatment:

Lab investigations were all within normal limits and he had a normal pituitary profile. CT head scan showed a mature right occipital infarct and a possible pituitary mass with suprasellar extension.Subsequent MRI scan of the brain confirmed an extensive right occipital infarct and also demonstrated a mega basilar artery which was virtually aneurysmal. There was no pituitary enlargement or mass lesion.  Stroke prevention strategies were adopted for this patient and he is undergoing neurorehabilitation.


Pinto et al. reported about 8 of 21 giant aneurysms studied were initially diagnosed as meningioma, pituitary adenoma and glioma. Completely thrombosed aneurysms may give more diagnostic challenges as angiography demonstates only avascular mass. Reliable imaging techniques and high index of suspicion are essential in establishing the diagnosis as there are certain characteristics in non-invasive imaging, typical of giant aneurysms.