What is the recommended follow-up for a hepatic mass found on Computed Tomography (CT) scan?

Follow-up Recommendations for Hepatic Mass Found on CT

For a hepatic mass found on CT scan, the recommended follow-up depends on the size of the lesion, presence of cirrhosis, and imaging characteristics, with lesions ≥1 cm requiring multiphasic imaging (CT or MRI) while lesions <1 cm should be monitored with ultrasound every 3-4 months.

Initial Assessment Based on Lesion Size

For Lesions <1 cm:

• Follow-up with ultrasound every 3-4 months 1
• Continue monitoring for at least 18 months; if stable over this period, transition to imaging every 6-12 months 1
• For subcentimeter nodules in high-risk patients (e.g., those with cirrhosis), follow-up surveillance within 6 months is recommended 1

For Lesions 1-2 cm:

• Evaluate with two different imaging techniques (multiphasic CT, MRI, or contrast-enhanced ultrasound) 1
• If both show classic arterial enhancement followed by washout, diagnose as HCC 1
• If classic enhancement pattern is not seen or observed with only one imaging modality, biopsy is recommended 1

For Lesions >2 cm:

• Only one imaging modality showing classic arterial enhancement is needed to diagnose HCC 1
• If classic enhancement is not observed, biopsy should be considered 1

Follow-up Based on Patient Risk Factors

In Patients with Cirrhosis:

• For lesions >2 cm with typical HCC features on dynamic imaging, no biopsy is needed - proceed with appropriate treatment 1
• For lesions with atypical enhancement patterns, biopsy is recommended 2
• Consider AFP testing as an adjunct to imaging (AFP >400 ng/mL has high positive predictive value for HCC) 1

In Patients Without Known Cirrhosis:

• More extensive workup is needed, including AFP testing 1
• If AFP is elevated, this supports HCC diagnosis 1
• Biopsy of non-tumor liver may be required to determine best treatment options 1
• Radiological imaging should be performed to exclude benign lesions 1

Specific Imaging Recommendations

Multiphasic Imaging Protocol:

• Use triphasic helical CT or dynamic contrast-enhanced MRI 1
• Include arterial phase, portal venous phase, and delayed venous phase 1
• For optimal detection, use thin reconstructed images (2.5 mm) 2
• Contrast injection rate of 4-5 mL/s is optimal for arterial phase imaging 2

Imaging Characteristics to Assess:

• Classic HCC pattern: intense arterial uptake/enhancement followed by contrast washout in delayed venous phase 1
• For indeterminate lesions, assess ancillary features such as:
  • Mild-to-moderate T2 hyperintensity
  • High signal intensity on diffusion-weighted imaging
  • Threshold growth (≥50% size increase in ≤6 months)
  • Enhancing or non-enhancing capsule
  • Mosaic architecture 1

Important Considerations and Pitfalls

Biopsy Considerations:

• Risk of needle-tract tumor seeding is 0.9-2.7% per year 1
• A negative biopsy does not rule out HCC if the nodule shows growth 1
• Avoid biopsy if surgical therapy is possible 1

Common Mistakes to Avoid:

• Relying solely on AFP for diagnosis (can be normal in up to 30% of HCC cases) 1
• Using only portal venous phase imaging (may miss hypervascular lesions) 2
• Confusing peripheral nodular enhancement patterns (important to distinguish between benign and malignant etiologies) 2

Multidisciplinary Approach:

• Patients with hypoattenuating liver lesions should be discussed in multidisciplinary teams 2
• Refer patients with chronic liver disease or cirrhosis immediately to hepatology 2
• Patients with known primary malignancies should be referred to oncology 2

By following these evidence-based recommendations, clinicians can ensure appropriate follow-up for hepatic masses found on CT, optimizing early detection of malignancy while avoiding unnecessary procedures for benign lesions.