From the Guidelines
Liver masses larger than 1 cm are concerning for malignancy and warrant further investigation. The size of the liver mass is a critical factor in determining the likelihood of malignancy, with masses larger than 1 cm having a higher risk of being hepatocellular carcinoma (HCC) 1. According to the most recent guidelines, a mass size of greater than 1 cm is considered abnormal and warrants further investigation, including multiphase contrast-enhanced CT or MRI, and possibly biopsy depending on imaging characteristics 1.
Key Factors Influencing Malignancy Risk
- Size of the liver mass: masses larger than 1 cm have a higher risk of being HCC
- Appearance of the mass on imaging: irregular borders, heterogeneous enhancement
- Rapid growth over time
- Patient risk factors: cirrhosis, hepatitis B or C, alcohol use disorder
Diagnostic Approach
For lesions smaller than 1 cm, a watch-and-wait approach with follow-up imaging in 3-6 months is often appropriate, especially in patients without underlying liver disease 1. For lesions larger than 1 cm, additional diagnostic workup is typically recommended, including:
- Multiphase contrast-enhanced CT or MRI
- Possibly biopsy depending on imaging characteristics
Context Matters
The context in which the liver mass is found is crucial in determining the likelihood of malignancy. For example, a 2 cm lesion in a patient with cirrhosis has a much higher risk of being HCC than the same size lesion in someone with healthy liver 1. This size threshold reflects the balance between detecting clinically significant malignancies while avoiding unnecessary procedures for benign lesions that are commonly found incidentally.
Recent Guidelines
The most recent guidelines recommend that liver nodules larger than 1 cm in size should be evaluated with dynamic contrast-enhanced CT/MRI or Gd-EOB-DTPA MRI, and that evidence of one or more radiological hallmarks of HCC, arterial hypervascularity, and venous/late-phase washout are considered indicative of HCC 1.
From the Research
Liver Mass Size and Malignancy Concerns
- The size of a liver mass that is concerning for malignancy is not strictly defined, but studies suggest that masses larger than 1-2 cm are more likely to be malignant 2.
- For hepatocellular carcinomas (HCCs), the performance of imaging modalities such as CT and MRI is better for tumors ≥2 cm, while performance is poor for HCCs <1 cm 2.
- Small hepatocellular carcinomas (less than 3 cm in diameter) are often associated with liver cirrhosis and can be difficult to distinguish from benign nodular lesions 3.
- A study on the treatment of small hepatocellular carcinomas with percutaneous RF ablation found that MR imaging was useful for evaluating the effectiveness of therapy, but that intratumoral regions of hyperintensity on T2-weighted images and enhancement on dynamic MR images did not always correlate with residual viable tumor 4.
Diagnostic Approaches
- Advanced imaging techniques such as multiphasic CT and MRI can help diagnose liver masses and distinguish between benign and malignant lesions 2, 5.
- Biopsies are usually not needed for benign liver tumors, as accurate diagnosis can be obtained using modern imaging techniques 6.
- For indeterminate liver nodules, there is insufficient data to recommend a specific diagnostic approach, such as biopsy or repeat imaging 2.
Benign Liver Tumors
- Benign liver tumors, such as hemangioma, focal nodular hyperplasia (FNH), and hepatocellular adenoma (HCA), are often asymptomatic and do not require treatment 6.
- HCAs are associated with the use of oral contraceptives or other steroid medications and may be complicated by malignant transformation 6.