An Insulinoma with Arteriovenous Shunt Formation Revealed by Computed Tomography Angiography: A Case Report.

We herein present the case of a 75-year-old female patient with an insulinoma accompanied by arteriovenous shunt formation. Although conventional contrast-enhanced computed tomography (CT) failed to localize the tumor, the lesion in the pancreatic body was successfully identified using magnetic resonance imaging, endoscopic ultrasound, selective arterial calcium injection testing, angiography, and CT arteriography performed during the selective intra-arterial contrast injection. Angiography revealed a stained nodule with a splenic arteriovenous shunt. CT arteriography further demonstrated the tumor and associated arteriovenous shunt, which were not clearly visualized on conventional contrast-enhanced CT. This case suggests that an arteriovenous shunt may contribute to reduced tumor conspicuity on conventional CT.