Focal Liver Lesions on Ultrasound: Differential Diagnosis of Cyst, Hemangioma, FNH, Metastasis, and HCC
The differential range of focal liver pathology includes cysts, abscesses, hematomas, primary tumors, and metastases (Hagen-Ansert, 2023). The sonographer must first determine the extrahepatic or intrahepatic location of the lesion. Intrahepatic masses may cause displacement of hepatic vascular branches, external bulging of the liver capsule, or posterior displacement of the inferior vena cava.
B-mode Features of Major Lesions
| Lesion | Ultrasound Features (B-mode) |
|---|---|
| Hemangioma | Classically uniformly hyperechoic (Kamaya et al., 2022) |
| Cyst | Anechoic, posterior acoustic enhancement, possible thin septa; internal contents (debris) in case of previous hemorrhage/infection (Kamaya et al., 2022) |
| Focal Steatosis/Spared Areas | Focal absence of fat — hypoechoic area in a hyperechoic liver; focal fat — hyperechoic areas; geometric boundaries, without mass effect or architectural distortion (Kamaya et al., 2022) |
Contrast-Enhanced Ultrasound (CEUS)
CEUS allows differentiation of metastases, hepatocellular carcinoma (HCC), hemangioma, and focal nodular hyperplasia (FNH) based on tumor-specific vascularization patterns (Strobel et al., 2009; Hagen-Ansert, 2023). A typical sign of hemangioma is peripheral nodular discontinuous enhancement on CECT/CEMR (Kamaya et al., 2022). A cyst on CEUS does not show peripheral rim or central vascularization/enhancement, whereas a metastasis demonstrates characteristic contrast behavior. CEUS is also used in the diagnosis of nodules in liver cirrhosis (Kim et al., 2014) and in characterizing complex cystic lesions (Corvino et al., 2015).
Lesions with Central Scar
The differential range of liver masses with a central scar includes: commonly — focal nodular hyperplasia, fibrolamellar carcinoma, HCC, hepatoadenoma, metastases; less commonly — atypical hemangioma and echinococcal cyst (Zaheer, 2023).
Diagnostic Value of the Method
According to a meta-analysis, CEUS has diagnostic efficacy in differentiating benign and malignant focal liver lesions (Friedrich-Rust et al., 2013). The absence of altered perfusion on CEUS helps confirm focal steatosis/spared area and exclude a true tumor (Kamaya et al., 2022).
Frequently asked questions
What CEUS pattern is typical for hemangioma?
Peripheral nodular discontinuous enhancement (on CECT/CEMR); in B-mode, hemangioma is classically uniformly hyperechoic (Kamaya et al., 2022).
How to distinguish a cyst from a cystic metastasis?
A cyst is anechoic, with posterior acoustic enhancement, thin septa, without peripheral rim and central vascularization/contrast enhancement (Kamaya et al., 2022).
What helps confirm focal steatosis?
Geometric boundaries, absence of mass effect and architectural distortion, as well as absence of altered perfusion on CEUS (Kamaya et al., 2022).
Which lesions present with a central scar?
Commonly — FNH, fibrolamellar carcinoma, HCC, hepatoadenoma, metastases; less commonly — atypical hemangioma and echinococcal cyst (Zaheer, 2023).
Does CEUS help differentiate metastasis, HCC, hemangioma, and FNH?
Yes, due to tumor-specific vascularization patterns (Strobel et al., 2009); meta-analysis confirms the value of CEUS in differentiating benign and malignant lesions (Friedrich-Rust et al., 2013).