A Giant Pituitary Adenoma Can Coexist with an Incidental Aneurysm: Look Beyond the Pituitary Adenoma and Don't Miss the Diagnosis.

An intracranial aneurysm in a pituitary adenoma (PA) is not uncommon; however, preoperative angiography is not clinically used as a routine screening test for PA patients. Therefore an intracranial aneurysm is often missed while diagnosing PA patients. When an aneurysm is missed in patients with pituitary tumors, the supporting power by the tumor to the blood vessels or aneurysm will disappear when the tumor is removed and patients may suffer intraoperative or postoperative aneurysm rupture, which may lead to fatal, catastrophic hemorrhage. Herein, we report a case of a PA patient with the signal shadow of vessel flow void, observed vaguely in the right internal carotid artery cavernous segment on magnetic resonance imaging, and a small aneurysm was found via digital subtraction angiography. In order to ensure the safety of surgery, we first performed embolization of the aneurysm and then resected the tumor.