Management of Incidental Hypodense Liver Lesion

Characterization of the Liver Lesion

The American College of Radiology suggests that a hypodense lesion with fluid attenuation is likely a simple hepatic cyst, which is the most common benign liver lesion 1, 3
The characterization of cystic liver lesions is based on two key features: number of lesions and architecture, with simple cysts typically appearing as homogeneous hypodense lesions on non-enhanced CT scans and showing no enhancement after contrast administration 1, 3
Simple hepatic cysts are characterized by fluid attenuation, similar to water density, and typically show strong signal on T2-weighted MRI sequences and low signal on T1-weighted sequences 1, 3

The American College of Radiology recommends MRI with contrast as the preferred modality for definitive characterization of cystic liver lesions, providing superior tissue characterization compared to CT 1, 2
MRI with contrast can establish a definitive diagnosis in up to 95% of liver lesions, with simple cysts showing no enhancement after contrast administration 1, 2
Contrast-enhanced ultrasound (CEUS) is an acceptable alternative to MRI if contraindicated, helping to distinguish between benign and malignant cystic lesions and reducing indeterminate diagnoses 1, 4, 5

For lesions less than 1cm, MRI with contrast is recommended for definitive characterization, and if MRI confirms a simple cyst, no further follow-up is needed 1, 2, 3
Lesions with atypical features, such as septations or mural thickening, may require biopsy for definitive diagnosis 1, 2, 3

Simple hepatic cysts are benign and typically require no treatment or follow-up once definitively characterized, with a sensitivity and specificity of ultrasound for diagnosis of around 90% 1, 3, 5
Incidental liver lesions are common, found in up to 15% of patients, and most are benign, but it's essential to rule out other potential diagnoses such as cystadenoma or metastatic lesions 1, 5