A rare variation of duplicated portal vein: left branch derived from splenic vein mimicking cavernous transformation

BACKGROUND: Duplication of the portal vein is a rare type of anatomic variant of the portal vein (PV) system that can be incidentally found and can lead to various challenges and consequences. Herein, we report an unusual case to increase our understanding of such anatomic variants. CASE PRESENTATION: A 67-year-old asymptomatic woman was diagnosed with a liver space-occupying lesion by ultrasonography on a routine physical examination. The laboratory examinations from a local hospital suggested that her liver function tests were normal. The liver appeared normal on pre-contrast enhanced CT images. However, there were multiple complex abnormalities of PV found on contrast-enhanced CT scans, including two independent sources of PV (duplication), preduodenal PV, circum-portal pancreas, mimic cavernous transformation, abnormal branches of PV, and transient abnormal perfusion in the left lobe of the liver. MRI showed fatty infiltration in the left lobe of the liver. CONCLUSION: This case extends our current understanding of the anatomical variations of the PV system. Knowledge of these complex and rare anatomical variations will help clinical doctors make a confident diagnosis or assist with proper planning of a surgical procedure.