Occult Amebic Liver Abscess as Cause of Extensive Inferior Vena Cava and Hepatic Vein Thrombosis.

The most common extraintestinal complication of Entamoeba histolytica is amebic liver abscess (ALA). Hepatic vein and inferior vena cava (IVC) thrombosis are rare but well-documented complications of ALA, typically attributed to mechanical compression and inflammation associated with a large abscess. We present a case of a previously healthy 43-year-old Canadian man presenting with constitutional symptoms and right upper quadrant abdominal pain. He was found to have thrombophlebitis of the IVC, accessory right hepatic vein, and bilateral iliac veins. Extensive investigations for thrombophilia were negative. Magnetic resonance imaging of the liver demonstrated a 3.2-cm focal area of parenchymal abnormality that was reported as presumptive hepatocellular carcinoma, and a 1.9-cm lesion in the caudate lobe with diffusion restriction and peripheral rim enhancement. Despite multiple biopsy attempts, a histopathological diagnosis was not achieved. Abdominal pain and fever 4 months later prompted repeat ultrasound demonstrating a 10.4- × 12.0-cm rim-enhancing fluid attenuation lesion felt to represent a liver abscess. Thick dark "chocolate brown" drainage from the lesion and positive serology for E. histolytica confirmed the diagnosis of ALA acquired from a previous trip to Cuba. The patient was started on treatment with metronidazole and paromomycin and repeat abdominal ultrasound demonstrated resolution of the abscess. This case is the first to demonstrate extensive IVC thrombosis secondary to a relatively small occult ALA and emphasizes the thrombogenic potential of ALA. Amebic infection should be considered as a rare cause of IVC thrombosis in the correct clinical context.