Radiological differentiation of intrasellar aneurysms from pituitary tumours.

The changes produced by aneurysms which project into the pituitary fossa as seen on plain films and radiological investigations have been reviewed and then compared with those caused by pituitary tumours. Erosion of the lateral wall of the sphenoid sinus and a filling defect within the cavernous sinus were features seen only in the aneurysm cases. A widened superior orbital fissure, non-filling of cavernous sinus (especially with a normal contralateral sinus), and, on Ct, unilateral sellar erosion, calcification and eccentric (in relation to sella) circular attenuation on enhanced scan, were more commonly associated with aneurysms. A completely eroded area of bone, a completely eroded fossa, a soft tissue opacity in the sphenoid sinus, bilateral displacement of the cavernous sinuses and, on CT, general enlargement of the fossa were seen only with cases of pituitary tumour. Abnormalities pointing to the presence of an aneurysm were seen in every case in which one was present. Our view suggests that innocuous techniques will demonstrate the presence of a vascular anomaly in the pituitary fossa and validates the policy in this Institute of relying on these measures and of dispensing with routine angiography as a preliminary to transsphenoidal hypophysectomy or microadenomectomy.