How Should an Incidental Liver Lesion Be Evaluated?

Clinical context changes the differential

A 2-cm lesion in a healthy young woman, a patient with cirrhosis and a patient with metastatic colon cancer are three different problems even before imaging characteristics are considered. The 2024 ACG focal liver lesion guideline emphasizes history of cancer, symptoms, medications, viral hepatitis risk and metabolic context as part of initial evaluation.

Start by asking whether imaging is adequate

Single-phase CT or ultrasound may identify a lesion without characterizing it. Multiphase contrast-enhanced MRI or CT can distinguish many common benign lesions—hemangioma, focal nodular hyperplasia (FNH), hepatocellular adenoma—and help identify malignant patterns. If available and not contraindicated, MRI often offers the most specific tissue characterization.

Common benign lesions usually do not need endless surveillance

A classic hemangioma or FNH in the appropriate clinical context generally requires no repeated imaging once confidently diagnosed. Hepatocellular adenoma is different because hemorrhage and malignant transformation risks depend on size, sex, subtype and hormonal/metabolic drivers; management may include stopping estrogen exposure, weight loss, surveillance or resection.

Cirrhosis changes the algorithm

In a patient at risk for HCC, lesion characterization should follow HCC-specific multiphasic imaging criteria. Routine biopsy of a classic HCC imaging phenotype is often unnecessary, whereas atypical or indeterminate lesions may require repeat imaging, alternate modality, multidisciplinary review or tissue diagnosis.

Biopsy is selective

Biopsy is useful when high-quality imaging cannot establish a diagnosis and the result will change management. It should not be the reflex first test for every incidental lesion because imaging can be diagnostic and some lesions have bleeding or seeding considerations.

A practical clinical approach

1. Review prior imaging for stability and growth.
2. Classify the patient as low risk or higher risk based on chronic liver disease and malignancy history.
3. Review medication/hormonal exposure and relevant laboratory tests.
4. Obtain multiphasic contrast MRI or CT if the lesion is indeterminate on initial imaging.
5. If imaging confidently establishes a benign lesion, stop unnecessary surveillance unless the lesion type requires follow-up.
6. Use HCC-specific algorithms in cirrhosis/HBV and multidisciplinary review for suspicious or indeterminate lesions.

Common errors to avoid

• Calling every incidental lesion a 'mass' that needs biopsy.
• Ignoring prior imaging.
• Using a generic incidental-lesion pathway in a patient with cirrhosis.
• Repeating scans indefinitely after a confident benign diagnosis.

What should trainees remember?

The essential question is not 'What is the lesion?' in isolation. It is 'What is the lesion in this patient, and is the imaging adequate to establish that diagnosis?'

Free further reading from Dr. Alan B. R. Thomson

See Dr. Thomson's Endoscopy and Diagnostic Imaging and Best Practice Guidelines in Hepatopancreaticobiliary Disorders.

Frequently asked questions

Is MRI always necessary?

No. But multiphasic MRI is often the preferred next test when a solid lesion remains indeterminate.

Do hemangiomas need surveillance?

A confidently diagnosed typical hemangioma generally does not require serial imaging in a low-risk patient.

Should every lesion be biopsied?

No. Biopsy is selective and is most useful when imaging remains indeterminate and pathology will change management.

References

1. Thomson ABR. Endoscopy and Diagnostic Imaging, Parts I-II. CAPstone Academic Publishers; 2012. ISBN 978-1477400579 and 978-1477400654.

2. Thomson ABR. Best Practice Guidelines in Hepatopancreaticobiliary Disorders. CAPstone Academic Publishers; 2024. ISBN 979-8861272735.

3. Frenette C, et al. ACG Clinical Guideline: Diagnosis and Management of Focal Liver Lesions. Am J Gastroenterol. 2024;119:1235-1271. doi:10.14309/ajg.0000000000002857.

4. American College of Gastroenterology. Focal Liver Lesions Guideline Highlights. 2025.