Portal Vein Invasion Secondary to Hepatic Hydatid Disease: A Rare Case Report

Background Hydatid cyst disease is a zoonotic parasitic infection caused by Echinococcus species and remains endemic in many regions worldwide, particularly in North Africa and the Mediterranean basin. The liver is the most commonly affected organ due to portal dissemination of the parasite. Although hepatic hydatid cysts are frequently encountered, vascular complications are uncommon, and portal vein invasion represents an exceptionally rare manifestation. This complication may lead to portal vein thrombosis, cavernous transformation, portal hypertension, and potentially life-threatening complications including anaphylaxis. Case Presentation We report the case of a 56-year-old male with a prior history of surgery for hepatic hydatid disease who presented with portal vein invasion mimicking portal vein thrombosis. Imaging studies revealed a hydatid cyst located in segment IV of the liver associated with portal venous obstruction and cavernomatous transformation. Color Doppler ultrasonography demonstrated absence of blood flow within the portal vein and collateral venous circulation consistent with portal cavernoma. Contrast-enhanced computed tomography clearly demonstrated communication between the multiloculated hydatid cyst and the portal vein, with multiple daughter vesicles extending from the portal trunk to the segmental portal branches causing vascular occlusion. Despite evidence of intraportal rupture, the patient did not develop anaphylactic shock or systemic allergic manifestations. Discussion Portal involvement in hepatic echinococcosis may occur through extrinsic compression, inflammatory invasion of the vascular wall, or direct rupture of the cyst into the portal circulation. Although all echinococcus larvae initially pass through the portal venous system, portal vein invasion remains exceedingly rare, likely due to the high pressure within the portal circulation. Chronic portal obstruction may result in extrahepatic portal vein obstruction, portal hypertension, and cavernous transformation. Radiologic imaging, particularly contrast-enhanced computed tomography, plays a crucial role in differentiating portal hydatid disease from conventional portal vein thrombosis by demonstrating intravascular daughter cysts and direct cysto-portal communication. Surgical management remains the treatment of choice and should address both the hydatid cyst and complications related to portal hypertension. Conclusion Portal vein invasion by hydatid cysts is a rare but serious complication of hepatic echinococcosis that may mimic portal vein thrombosis. Recognition of this entity is essential, particularly in endemic regions and in patients with previous hydatid surgery, in order to optimize diagnosis and management. Early identification through advanced imaging modalities may help prevent severe complications and improve clinical outcomes.