Alveolar echinococcosis of liver: a diagnostic problem in a nonendemic area.

Alveolar echinococcosis is a parasitic disease primarily invading the liver. Due to its aggressive nature, it invades the adjacent structures and can even metastasize to distant organs. The appearance of hepatic involvement on computed tomographic scan is characteristic, but not specific, with areas of calcification seen within a hypoenhancing mass. Although magnetic resonance imaging may better define the extent of the disease, it often misleads the radiologist, especially if the lesion is devoid of cystic component(s) and if it occurs in nonendemic areas. Knowledge of the imaging appearance may prompt serological evaluation and aid in making an early diagnosis and planning appropriate treatment of this uncommon fatal disease, especially in nonendemic areas.