Echinococcal Cysts in the Liver- The physical examination revealed hepatomegaly with a palpable hepatic mass. Laboratory tests showed a normal white-cell count and a normal absolute eosinophil count. Ultrasonography (Panel A) and computed tomography (Panel B) of the abdomen revealed a large cyst in the right lobe of the liver, containing hydatid membranes (black arrows) and daughter vesicles (white arrows). An enzyme-linked immunosorbent assay indicated an anti-echinococcus IgG antibody index of 16.7 in the patient’s blood (normal value, ≤11). Hydatid disease is caused by the echinococcus tapeworm. Dogs are the definitive host; the infection is transmitted when eggs shed in their stool are ingested by humans or other animals. #clinical #NEJM #echinoccocal #cyst #liver #hepatic #radiology #CT #ultrasonography #echinococcus #granulosis #hydatid