Sellar Aneurysm: Masquerading As Pituitary Macroadenoma With Hypopituitarism

Fig 3A &B. MR-Angio of the Circle of Willis Showing Vascular Aneurysm A 40 year old married male presented with moderate to severe intermittent headache and progressive diminution of vision in both eyes for the last eight months. He had history of easy fatigability, cold intolerance and postural giddiness but refused any features suggestive of hypogonadism. CECT Brain revealed a pituitary mass consistent with pituitary macroadenoma (FIG1). Hormone evaluation of pituitary functions suggested low T4 with inappropriately normal TSH, low cortisol, low basal HGH, mildly elevated serum prolactin and normal LH, FSH, and testosterone. We were called a day before the scheduled trans-sphenoidal surgery and in view of hormone assays showing central hypothyroidism we suggested to make the patient euthyroid and asked for further radiological evaluation. Contrast enhanced MRI Brain (FIG.2A, 2B) revealed a large sellar mass with suspicion of a partially thrombosed intrasellar aneurysm arising at the junction of left anterior cerebral artery and anterior communicating artery. Carotid angiography, (FIG.3A, 3B), showed a giant aneurysm in relation to the anterior part of the circle of Willis arising from anterior cerebral artery. Although sellar aneurysms presenting as pituitary adenomas or hypopituitarism are reported earlier (1-4), thrombosed aneurysm can be particularly difficult to differentiate from the macro-adenoma and index of suspicion needs to be high. The diagnosis of this rare but interesting entity is vital for the proper management to avoid catastrophic complications like hemorrhage and visual loss.