hydatid cyst, a cyst in the liver that contains larvae of the tapeworm Echinococcus granulosus, whose eggs are carried from the intestinal tract to the liver via the portal circulation. Patients are generally asymptomatic, except for hepatomegaly and a dull ache over the right upper quadrant of the abdomen. Radiological tests are used in diagnosis, and, because no medical treatment is available, surgical removal of the cyst is indicated. Should not be confused with hydatid mole.
