Multimodality imaging of common and uncommon cystic focal liver lesions.

Cystic lesions of the liver are frequently encountered in clinical practice. In general, they can be classified as developmental, neoplastic, infectious, inflammatory, or miscellaneous lesions. Most cystic focal liver lesions have specific sonographic, computed tomographic, and magnetic resonance imaging features. These features help narrow, in combination with critical clinical information, the differential diagnosis and negate the need for biopsy or further diagnostic investigations in many patients. The purposes of this essay are to illustrate the characteristic sonographic, computed tomographic, and magnetic resonance imaging appearances of a gamut of both common and uncommon cystic focal liver lesions, to correlate these imaging findings with gross and microscopic pathology features, and to emphasize the essential information that allows differentiating among cystic hepatic lesions. Among others, imaging features that are important to recognize include the size and shape of the cyst; the presence and thickness of a cyst wall; the presence of calcifications, mural nodularity, debris, and septations; the density and signal intensity spectrum along with the enhancement pattern; the presence of communication with the biliary tree; and the presence of pericystic changes in the hepatic parenchyma. Familiarity with the complete spectrum of cystic focal liver lesions and a thorough understanding of their classic imaging appearances will undoubtedly allow a more definitive diagnosis and shorten the diagnostic workup.