Intra-hepatic arterioportal shunt mimicking a metastatic liver tumor: report of a case.

The differential diagnosis of an arterioportal shunt (APS) is difficult and important. We report a case of an intra-hepatic APS mimicking a metastatic liver tumor on imaging scans in a patient without hepatic cirrhosis. The patient was a 64-year-old woman, who had undergone low anterior resection of the rectum for advanced rectal cancer, followed 2 months later by right hemihepatectomy, including the middle hepatic vein, for a synchronous metastatic liver tumor. About 2 years after the hepatectomy, a follow-up CT scan showed a new mass in the remnant liver, suggestive of a metastatic liver tumor, the assumption of which was further supported by an elevated serum carcinoembryonic antigen (CEA) level. However, the findings of magnetic resonance imaging were not consistent with a malignant tumor, and Doppler ultrasonography showed a low echoic area connected with the portal vein branch and the hepatic artery branch. Thus, we diagnosed intra-hepatic APS. The patient remains well without signs of growth of the hepatic lesion, although with fluctuating serum CEA levels.