Differentiating Cystic Liver Lesions: A Review of Imaging Modalities, Diagnosis and Management.

Hepatic cysts (HCs) are frequently discovered incidentally on abdominal imaging. The prevalence of HCs has been reported as high as 15-18% in the United States. Although most cysts are benign, some are malignant or premalignant. It is important to diagnose cystic lesions in order to properly manage them. Imaging with conventional ultrasound, computed tomography, magnetic resonance imaging, or contrast-enhanced ultrasound can be used to further characterize and diagnose HCs. Ultrasound is typically the first-line imaging modality, whereas more advanced imaging can help narrow down the specific lesion. Contrast-enhanced ultrasound is a newer modality, recently approved in the United States, which offers non-invasive evaluation in real-time. The first step in diagnosis is stratifying risk by differentiating simple and complex cysts. There are several features that can help identify HCs, including septae, mural consistency, calcifications, and quality of cystic fluid. Simple cysts are mainly congenital cysts, but also occur in polycystic liver disease. Complex cysts include mucinous neoplasms, echinococcal cysts, hemorrhagic cysts, cystic hepatocellular carcinoma and other rare lesions. Treatment is indicated in symptomatic cysts or those suspicious for malignant or premalignant features. Treatment modalities include fenestration, aspiration sclerotherapy, or surgical resection.