Portal vein aneurysm with complete spontaneous regression after 10 years using conservative treatment.

Portal vein aneurysms are rare vascular findings for which there are no optimal treatment guidelines. The scarce knowledge about their etiology, natural history, and management mean that there are limited treatment options. Here, we describe the case of a 69-year-old woman who presented with a 35-mm hypoechoic area in the hilar region of the liver that was accidentally detected by ultrasonography. Color Doppler ultrasonography demonstrated a mass with internal flow contiguous with portal vein, which was confirmed to be a portal vein aneurysm by computed tomography. Given that she experienced no symptoms of impending rupture or thrombosed aneurysms, we adopted a conservative treatment. Follow-up imaging demonstrated slow progression of the aneurysm diameter, from 35 to 43 mm at 3 years, and to 48 mm at 6 years; subsequent imaging after 6 years did not show any change in the diameter from 48 mm. However, the portal vein aneurysm completely regressed with no complications at a follow-up of over 10 years. This case suggests that long-term observation with periodic imaging may be an acceptable therapeutic option for asymptomatic portal vein aneurysms that show no short-term improvement. This case report contributes to a better understanding of how to treat this rare disease.