Echinococcosis of the Liver

A 65-year-old woman was admitted to the hospital with abdominal discomfort and constipation. A nontender mass was palpated in the right hypochondrium.

CT scan of the liver (A) revealed a large cystic structure with daughter cysts-a presentation that is consistent with hydatid disease of the liver. The hydatid cyst was surgically removed, and the patient's recovery was uneventful.

Ultrasonography of the upper abdomen of a 72-year-old woman admitted to the hospital for acute pyelonephritis demonstrated an incidental finding-a cystic lesion in the liver. The CT scan showed calcification within the cyst wall (B). Hydatid disease was confirmed by a high antibody titer to hydatid antigen. Oral mebendazole therapy was prescribed for this patient, and she was discharged from the hospital.

Drs Dimitrios Papaioannides and P. Stasinos of Arta, Greece, C. Giafis of Argostoli, Greece, and N. Akritides of Ioannina, Greece, report that hydatid disease, or echinococcosis, is caused by the tapeworm Echinococcus granulosus, which is found throughout the world, particularly in sheep-rearing areas. Cases have been reported in the southwestern United States, Alaska, and the lower Mississippi valley.

The organism lives in dogs; sheep, cattle, and humans are intermediate hosts. Human infection follows ingestion of contaminated water or vegetation, as well as hand-to-mouth transmission of canine feces that carry the tapeworm eggs. The embryos of the ingested eggs emerge, migrate through the gut to the portal blood vessels, and develop into hydatid cysts in the lungs, brain, spleen, bones, and kidney-but especially in the liver.

Hydatid cysts of the liver may be asymptomatic or can present with pain in the right hypochondrium. Very large lesions can cause abdominal distension and discomfort. A secondarily infected cyst causes fever and pain. Pleuritic discomfort; abdominal pain and tenderness; and allergic manifestation, such as urticaria and anaphylaxis, can result from rupture of a hydatid cyst. The consequences of the release of daughter cysts that seed the peritoneal cavity is another serious complication.

Surgical excision of the cysts offers the best chance of cure; care must be taken to avoid cyst rupture and consequent dissemination of daughter cysts. Mebendazole and albendazole are used for treatment of small and asymptomatic hydatid cysts.