There are 3 reports where the authors have identified a pre-hepatic mechanism causing PHT in LH. ^[4,5,11] El Fortia et al., reported a 60-year-old woman with perihilar splenic varices without other signs of PHT. ^[4] Ultrasound alone was useful in identifying compression at the splenic hilum by a calcified hydatid cyst, and, splenectomy was performed to resolve the PHT. In the other two cases, the obstruction was at the hepatic hilum causing portal cavernomatosis. ^[5,11] One of these required shunt surgery ^[5], while the other ^[11] was detected to have multiple other intrahepatic cysts on CT and MR imaging. The latter case was planned for liver transplantation due to liver failure, but died awaiting surgery following a variceal bleed.

From these cases, it may be ascertained that pre-hepatic PHT is usually caused by a unilocular hydatid cyst. CT scan would be useful for delineating the obstruction. Treatment in most cases would be surgical removal of the obstructing cyst, or, porto-systemic shunt surgery.

Cirrhosis of the liver with portal fibrosis can occur in advanced cases of LH. This mechanism has been reported in 10 cases by 3 authors. ^[7,10,13] In most of these patients, the offending organism was Echinococcus alveolaris. This is not surprising, as infiltrative growth of E. alveolaris into the bile ducts is known to cause cirrhotic changes in the liver. These patients are likely to present with ascites, and other signs of liver cell failure. The disease is progressive with a poor prognosis. Treatment is supportive, as radical surgery is mostly unsuccessful. ^[6,13] Liver transplantation for advanced alveolar echinococcosis (EA) was performed for 17 patients by Bresson-Hadni and colleagues. ^[13] Fifteen of these patients had PHT, which in 7 was of the Budd-Chiari type, and in the rest was hepatic. There was a higher recurrence rate and lower survival in patients with EA than in patients with livers transplanted for other indications. Thus, liver transplantation cannot be routinely recommended for all patients with EA.

There are twelve instances of post-hepatic PHT, or the Budd-Chiari syndrome due to LH described in literature. ^[2,6,8,9,13] Of these, nine patients had EA. In alveolar disease, the post-hepatic mechanism often co-exists with cirrhosis, and the treatment and prognosis for such patients is similar to those described by Bresson-Hadni ^[13] (vide supra). In five patients ^[2,6,8,9], there was localized obstruction to the hepatic veins or the inferior vena cava. This focal obstruction was caused by E. granulosus in three, and E. alveolaris in two patients. In all five patients, the liver functions were normal. CT was effective in diagnosis by identifying compression at the caval site, presence of collaterals, non-visualization of hepatic veins, and, ascites. ^[6,8,9] Because of the unusual location of the disease, different strategies have been adopted by different authors. Combined resection of the liver and vena cava was performed by Mekeel et al., ^[2], though this has been debated by some as being too radical for benign disease. ^[14] A novel therapy has been successfully attempted by Vogel and colleagues in the form of percutaneous stenting of the hepatic veins. ^[6] The authors recommend this approach in selected patients of posterior localized alveolar disease where liver function is normal. They believe that resection for such cases is often only palliative with short-lasting benefit, thereby not justifying the associated morbidity.

We feel that due to the rarity of the condition, no recommendation can be made, and the treatment needs to be individualized. Operative resection seems to be an attractive option more for unilocular disease. The patients with LH and chronic Budd-Chiari syndrome would be very difficult to identify in the clinical setting. Ascites may be the only symptom, and liver functions may be normal. A high index of suspicion is required, along with careful interpretation of the subtle CT findings. Direct measurement of portal pressure by invasive techniques is not practical in the clinical setting.

When the ascites is acute in onset, the first suspicion must be of cyst rupture, and urgent steps must be taken to provide definitive treatment and prevent anaphylaxis. A single case of acute Budd-Chiari syndrome due to unilocular cyst has been reported. ^[8]