What are liver hemangiomas, what causes them, and how are they treated?

Liver Hemangiomas: Diagnosis, Causes, and Treatment

Liver hemangiomas are benign vascular tumors that rarely require treatment unless they are large, symptomatic, or show rapid growth. 1

What Are Liver Hemangiomas?

• Hepatic hemangiomas are the most common benign liver tumors, consisting of clusters of blood-filled cavities lined by endothelial cells and fed by the hepatic artery 2
• Prevalence estimates range from 0.4% to 8% of the general population, with higher prevalence in women 3
• They are considered developmental malformations of vascular origin rather than true neoplasms 3
• Based on size, they can be categorized as:
  • Small (<2 cm): Typically appear uniformly echogenic on ultrasound 3
  • Medium (2-5 cm): Mainly echogenic on imaging 3
  • Large/Giant (>5 cm): Show mixed echogenicity and have higher risk of complications 3, 1

Causes and Risk Factors

• The exact pathophysiology of liver hemangiomas is not fully understood, but they are considered congenital vascular malformations 4
• Unlike hepatocellular adenomas, liver hemangiomas do not have a well-established association with estrogen exposure, though they are more common in women 3
• Genetic factors may play a role, but specific genetic markers have not been clearly identified 4
• Most hemangiomas are discovered incidentally during imaging studies performed for unrelated conditions 2

Diagnosis

• Most hemangiomas are asymptomatic and discovered incidentally on imaging 2
• Diagnostic imaging features include:
  • Ultrasound: Small hemangiomas appear uniformly echogenic, while larger ones show mixed echogenicity 3
  • Contrast-enhanced ultrasound (CEUS): Shows characteristic peripheral nodular enhancement (74%) in arterial phase and complete (78%) or incomplete (22%) centripetal filling in portal venous and late phases 3
  • MRI: Preferred for inconclusive cases with 95-99% accuracy for diagnosing hemangiomas 1
• Biopsy is generally not recommended due to bleeding risk and is only necessary when imaging is inconclusive and malignancy cannot be excluded 1

Treatment Approach

• The vast majority of liver hemangiomas require no treatment as they are asymptomatic and follow a benign course 1, 5
• Treatment decisions should be based on:
  • Size: Giant hemangiomas (>5 cm) have higher risk of complications 1
  • Symptoms: Abdominal pain or compression of adjacent structures 5
  • Growth rate: Rapidly enlarging lesions may warrant intervention 1
  • Complications: Rupture (rare but serious) 1, 6

Management Algorithm:

1. For asymptomatic, typical hemangiomas <5 cm:

   • No intervention required 1
   • No routine follow-up needed 1

2. For giant hemangiomas (>5 cm):

   • If asymptomatic: Observation with periodic imaging 1
   • If symptomatic or growing: Consider intervention 1, 5

3. For symptomatic hemangiomas:

   • Surgical options: Enucleation (preferred) or hepatic resection 7
   • Non-surgical options: Transcatheter arterial embolization or radiofrequency ablation 4

4. For pregnant women with hemangiomas:

   • Small/medium hemangiomas: Generally safe with no monitoring required 3
   • Giant cavernous hemangiomas (>5-10 cm): Monitoring recommended during pregnancy 3
   • For very large hemangiomas (>10 cm) in women planning pregnancy: Consider treatment before conception 1

Complications and Special Considerations

• Rupture is rare (<1% overall) but risk increases with size (3.2% for lesions >4 cm, 5% for lesions >10 cm) 1
• Peripherally located and exophytic lesions have higher rupture risk 1
• During surgical management of giant hemangiomas, early vascular control techniques are essential to minimize bleeding risk 7
• Unlike hepatocellular adenomas, hemangiomas have no risk of malignant transformation 5