간종괴의 초음파 감별 진단
Differential Ultrasonographic Diagnosis of Liver Masses
Article information
Trans Abstract
Hepatic masses include a variety of benign and malignant lesions originating in the liver, and ultrasonography is one of the most basic and essential imaging tools for evaluating these lesions. This review comprehensively summarizes the ultrasonographic findings of hepatic masses by lesion type and examines the interpretation and clinical significance of each. In regions like Korea, where chronic liver disease is highly prevalent, the role of ultrasonography is particularly important. Accurate diagnosis and formulation of treatment strategies require skilled interpretation of ultrasound images.
INTRODUCTION
The liver is a large organ with abundant blood flow, making it susceptible to various tumorous lesions. Hepatic lesions are often described as either nodules or masses. A nodule generally refers to a small, rounded lesion, often less than 2 cm, while a mass typically denotes a larger or potentially more aggressive lesion over 2 cm in size [1]. Hepatic masses are generally detected through imaging, and ultrasonography is a primary tool in initial evaluation due to its accessibility, safety, and repeatability. Hepatic masses range from benign lesions such as simple cysts to malignant ones like hepatocellular carcinoma (HCC), and distinguishing between them is crucial for determining patient prognosis [2]. In areas with high prevalence of liver disease, early diagnosis and active management are critical, requiring high accuracy in sonographic assessments. Ultrasonographic evaluation allows real-time observation of the structure and blood flow of intrahepatic lesions. Important features to consider include lesion location, size, shape, number, internal echo pattern, relationship to adjacent structures, marginal findings (e.g., halo), and posterior shadowing. Especially, lesion shape, margin, internal echo homogeneity, and changes in surrounding vasculature provide key clues for differentiating benign from malignant masses.
ULTRASONIC FINDINGS OF VARIOUS LIVER MASSES
Hepatic Cyst
One of the most common benign liver lesions, hepatic cysts appear on ultrasound as well-demarcated anechoic structures. Posterior acoustic enhancement is a typical feature due to the unattenuated p assage o f s ound w aves t hrough f luid. L ateral acoustic shadowing indicates a clear boundary with surrounding tissues (Fig. 1).
Hepatic Cyst. Hepatic cyst (red arrow) is observed as an anechoic structure with clear boundaries. Posterior acoustic enhancement is a typical feature of cystic lesions.
Hemangioma
The most common benign tumor of the liver, hemangiomas usually show homogeneous hyperechoic patterns. In cases of fatty liver, they may appear hypoechoic and require differentiation. A peripheral echogenic rim reflects vascular distribution. Lesions over 2.5 cm often show posterior enhancement (Fig. 2).
Hepatic Hemangioma. Hepatic hemangioma (red arrow) shows homogeneous hyperechoic echotexture. The peripheral echogenic rim is a characteristic finding of hemangioma.
HCC
HCC typically arises against a background of chronic liver disease or cirrhosis. Early lesions appear small, hypoechoic, and well-defined. As they grow, they may show mosaic or mixed echo patterns, internal septations, halos, central necrosis, and more. Lesions over 3 cm may show nodule-in-nodule or pseudoglandular patterns. Associated findings include cirrhosis, portal vein thrombosis, daughter nodules, and hump sign, indicating progression (Fig. 3) [3].
Hepatocellular Carcinoma. Hepatocellular carcinoma (red arrow) initially appears as a small, hypoechoic lesion with clear margins, but as it grows, it shows various changes such as mixed or mosaic echotexture, internal septation, peripheral halo, and central necrosis. The image shows findings of hump sign, halo, and portal vein thrombosis.
Intrahepatic Cholangiocarcinoma
A malignant tumor originating from intrahepatic bile ducts, it presents with irregular margins, satellite nodules, and ductal dilation. It may show homogeneous internal echoes with hyperechoic foci and posterior shadowing due to mucus or calcification. Clonorchiasis may be a predisposing factor (Fig. 4).
Intrahepatic Cholangiocarcinoma. Intrahepatic cholangiocarcinoma (red arrow) is a malignant tumor that arises from intrahepatic bile ducts and generally presents with irregular margins and bile duct dilatation. When bile duct dilatation is absent, differentiation is difficult.
Metastatic Liver Cancer
Typically from other organs, metastases show varied sonographic features: bull’s eye sign, target sign, and cluster sign. Usually multiple, but 5–12% may be solitary. Echo patterns include hyperechoic (68%), hypoechoic (15%), cystic, or calcified/mixed types (Fig. 5).
Metastatic Liver Cancer. Typical findings of metastatic liver cancer (red arrow) include bull's eye sign and target sign. Lesions are generally multiple, but can appear as solitary lesions in 5–12% of cases.
Liver Abscess
Infectious lesions show changing sonographic features depending on the stage of inflammation. They are initially hyperechoic, later hypoechoic, and eventually cystic. “Dirty” posterior enhancement suggests air or necrosis. Margins are irregular. Clinical signs and blood tests aid diagnosis (Fig. 6).
Liver Abscess. Liver abscesses (red arrow) might appear as hypoechoic or complex cystic lesions with irregular margins and internal debris. Posterior enhancement and air echoes would be noted depending on the abscess stage.
Fatty Liver Lesions
Resulting from localized fat infiltration or sparing, these lesions are commonly located near segment 4, the gallbladder, or subcapsular regions. Focal fat sparing typically appears hypoechoic with preserved vascular architecture and may change over time. Oval shape and distinct echo contrast with surrounding tissue are characteristic (Fig. 7) [4].
Fatty Liver Lesion. Fatty liver lesion (red arrow) generally appears as a hypoechoic lesion, but without vascular structure deformation, and may change over time. Features include an oval shape and a distinct echogenic contrast with surrounding liver parenchyma.
Eosinophilic Abscess
Associated with eosinophilia, this lesion appears as 1–3 cm hypoechoic lesions. Margins are unclear, but the internal structure is relatively homogeneous. Differentiation from metastatic lesions is needed. Hematologic findings like eosinophilia assist in diagnosis (Fig. 8) [5].
Eosinophilic Liver Abscess. Eosinophilic liver abscess is characterized by 1–3 cm hypoechoic lesions. Margins are unclear and the internal structure is relatively homogeneous.
Focal Nodular Hyperplasia
A benign lesion, due to congenital vascular malformation, is common in women in their 20s to 40s. It shows a central scar with radial hyperechoic extensions on ultrasound and is typically solitary and well-defined (Fig. 9).
Focal Nodular Hyperplasia. The central scar of focal nodular hyperplasia (red arrow) appears as a radially spreading hyperechoic area; typically presents as a single lesion with well-defined margins.
Hepatic Adenoma
A benign lesion, arising in non-cirrhotic livers, is frequently seen in women on oral contraceptives. It is usually solitary, with hemorrhagic tendencies and rare malignant transformation. Sonographic appearance varies. Contrast-enhanced ultrasound (CEUS) may show lack of central enhancement (Fig. 10).
Hepatic Adenoma. Hepatic adenoma (red arrow) shows various non-specific sonographic features that make differentiation from other diseases difficult. In fatty liver, it may appear isoechoic or hypoechoic.
DIFFERENTIAL DIAGNOSIS BETWEEN BENIGN AND MALIGNANT LESIONS
Benign lesions typically have smooth margins, preserved surrounding vascular architecture, and homogeneous internal echoes, usually anechoic or hyperechoic (except in fatty liver background). A peripheral hyperechoic rim suggests hemangioma.
Malignant lesions tend to be irregular, hypoechoic, and heterogeneous, becoming mixed echoic as they grow. Cirrhosis increases suspicion, but HCC can also arise in chronic hepatitis B or metabolic dysfunction-associated steatotic liver disease without cirrhosis. Malignant features include irregular margins, disrupted vasculature, portal vein thrombosis, halo sign, hump sign, daughter nodules, and umbilication. Interpreting these complex signs is crucial.
CONCLUSION
Ultrasound alone is insufficient for complete liver mass diagnosis and must be integrated with serum tumor markers (e.g., alpha-fetoprotein), liver function tests, patient history, and risk factor assessment. Further evaluation with CEUS [6], computed tomography, or magnetic resonance imaging may be required. High-risk individuals need regular ultrasound follow-ups to monitor changes and guide biopsy or treatment decisions.
Thus, differential diagnosis of liver masses via ultrasound is central to clinical management and treatment planning. Deep understanding and ample experience with sonographic features improve diagnostic accuracy and early detection. Especially for HCC, early diagnosis directly improves survival, warranting continued attention and training in liver mass ultrasonography.
Notes
ACKNOWLEDGEMENTS
None.
FUND
None.
CONFLICTS OF INTEREST
No potential conflict of interest relevant to this article was reported.
AUTHOR CONTRIBUTIONS
J.Y.J. and T.R. designed the study. Y.C. and S.W.J. were responsible for the data acquisition. T.R. and Y.C. analyzed the data. J.Y.J. wrote the first draft of the manuscript. J.Y.J. and S.W.J. critically revised the manuscript. J.Y.J. supervised the project. All authors read and approved the final manuscript.