It is a parasitic infection with Echinococcus granulosus. The infection occurs by direct contact with a dog (which is the final host, while sheep and cattle are the intermediate hosts) or via contaminated water or food. Embryos migrate through the intestinal mucosa and reach the liver through the portal vein. Cysts formed in the liver may grow 2–3 cm per year. When small, these are identical to simple liver cysts, while larger cysts form daughter cysts and membranes that can slough off or rupture. Pathognomonic imaging features are presence of calcifications seen in the capsule, best appreciated on CT (Fig. 1), or evidence of a floating membrane within ruptured lamellae (Fig. 2). The most severe complication is cyst rupture within the abdominal cavity.