INTRODUCTION: Hydatid disease, or Echinococcosis, most commonly affects the liver, although echinococcal cysts are found in the lungs in 25% of cases. Pulmonary hypertension (PH) from echinococcal embolization to the pulmonary vasculature is quite rare, however, usually occurring with cardiac involvement. We report a patient with echinococcal embolic PH without cardiac involvement treated with targeted pulmonary vascular therapy and resection of the hepatic cyst.
CASE PRESENTATION: A 37-year-old Egyptian male was diagnosed with a single hepatic echinococcal cyst 7 years prior to our evaluation. He was treated with albendazole and praziquantel with intermittent compliance. Four years later, CT scanning of the chest revealed bilateral cavitating lung cysts. A thoracoscopic biopsy revealed an echinococcal cyst and pulmonary vascular changes consistent with PH. He was referred to our center. A right upper quadrant ultrasound revealed a 15 cm hydatid cyst in the right lobe of the liver. A Ventilation/Perfusion scan revealed multiple bilateral segmental perfusion defects and normal ventilation. No cysts were seen in the heart or thoracic vena cava on magnetic resonance angiography. A transthoracic echocardiogram showed a normal left ventricle, moderate right ventricular dilation and an RV systolic pressure of 81mmHg. During a 6 minute walk test (6MWT) the patient ambulated 1050 ft. A right heart catheterization showed a right atrial pressure of 9 mmHg, a pulmonary artery pressure of 106/37 mmHg (mean PA 66 mmHg), and a cardiac index of 2.2 L/min/m2; no wedge pressure was measured. He was treated with furosemide, albendazole, bosentan, and intravenous epoprostenol with rapid clinical and hemodynamic improvement, and the patient underwent resection of the hepatic cyst. The cyst encased the right hepatic vein and the cavity was open to the lumen of the inferior vena cava (IVC). The cyst and part of the IVC were excised. He was discharged one month later with the addition of sildenafil, and epoprostenol was discontinued. By 11 months, he reported a return of his exercise tolerance to preoperative baseline (6MWT distance = 1305 ft) on sildenafil, bosentan and albendazole, and he had returned to work by one year after surgery.
DISCUSSIONS: E. granulosus is the most common form of the human tapeworm Echinococcus. Endemic to the Middle East, this parasite has a lifecycle which involves a definitive host (usually a wild dog) which passes eggs in its feces, and an intermediate host (usually a grazing animal) which ingests the eggs. Humans are “accidental” intermediate hosts. Eggs typically encyst in the liver, but may travel to the lungs and other organs. Severe PH in echinococcosis is rare and is usually attributable to rupture of a cardiac cyst with embolization to the lungs. Our patient had no cardiac cysts; the intraoperative findings suggest that chronic seeding of cyst contents into the IVC with embolization to the pulmonary circulation had occurred. Our patient not only had histologic changes consistent with pulmonary arterial hypertension (PAH), but also responded to PAH therapy, demonstrating the potential importance of a small vessel arteriopathy in this disease. Case reports of acute and chronic echinococcal pulmonary emboli with PH describe a poor prognosis, with death occurring within months. In this case, peri-operative treatment with bosentan and epoprostenol permitted the safe resection of the hepatic cyst, eliminating a possible source for further embolization. Continued treatment of his PH has led to functional improvement for more than one year.
CONCLUSION: While the prognosis for PH in the setting of echinococcosis is poor, targeted therapy for PH may be clinically effective for this rare condition.
DISCLOSURE: William Bulman, Grant monies (from industry related sources) Research support from Actelion Pharmaceuticals and Pfizer, Inc.