Enlargement of an incidental internal carotid artery aneurysm embedded in pituitary adenoma associated with medical shrinkage of the tumor: Case report

BACKGROUND: Currently, transsphenoidal surgery (TSS) is the preferred method for surgical treatment of intrasellar pituitary adenomas. However, it carries some risk of intraoperative arterial injuries, which is mainly attributed to direct iatrogenic rupture of the internal carotid artery (ICA). There is anecdotal evidence suggesting that intracranial aneurysms are coincidentally found significantly more frequently in the setting of pituitary adenomas than when the incidence is compared to other intracranial neoplasms. The exact cause of this discrepancy remains unclear, but it certainly raises concerns about the potential existence of an ICA aneurysm, which might be encountered during TSS and in some cases may cause hemorrhagic complications. CASE DESCRIPTION: We present a case of a patient who was found to have a growth hormone (GH)-secreting pituitary adenoma and a coexisting cavernous ICA aneurysm which was embedded within the tumor. The patient underwent medical treatment of the adenoma. However, shrinkage of the tumor was associated with enlargement of the observed aneurysm, warranting endovascular intervention. CONCLUSIONS: This case report is an illustration for physicians to be conscientious about the potential danger posed by the coexistence of an intratumoral aneurysm in the setting of a pituitary adenoma. Special attention should be given to recognition of an intrinsic flow void signal on the presurgical imaging of the tumor, and if observed, magnetic resonance angiography (MRA) should be performed for preoperative planning. If MRA is not performed routinely, detailed review of high-resolution magnetic resonance imaging is recommended to detect any flow artifacts suggestive of an aneurysm.