Infantile hepatic hemangiomas (IHH) are liver lesions composed of large endothelial-lined vascular channels seen in fetuses and neonates. They are not to be confused with hepatic epithelioid hemangioendothelioma, which occurs in older patients.
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Terminology
These benign tumors were previously referred to as hepatic infantile hemangioendotheliomas, but as they are similar to hemangiomas elsewhere in the body, they have been reclassified as hemangiomas by the International Society for the Study of Vascular Anomalies (ISSVA).
Epidemiology
Infantile hepatic hemangiomas occur in fetuses and neonates and have been detected in utero as early as 16 weeks of gestation. It is the most common benign liver mass in pediatric patients, typically occurring <6 months of age 9.
Associations
hypothyroidism: probably due to high levels of type 3-iodothyronine deiodinase activity produced by hemangiomas 3
hemangiomas elsewhere in 10% of cases
Clinical presentation
Infantile hepatic hemangiomas have substantial arteriovenous shunting which may lead to fatal cardiovascular compromise and hydrops fetalis. It may present as hepatomegaly since the entire liver is involved in most cases.
In addition, fetuses may also develop hemolytic anemia, thrombocytopenia, and consumptive coagulopathy (Kasabach-Merritt sequence).
If these tumors are not detected prenatally, neonates may present with unexplained congestive heart failure.
Pathology
Infantile hepatic hemangiomas are histologically similar to hemangiomas (strawberry nevus) but distinct from both adult type cavernous hemangiomas which are venous malformations and angiosarcomas.
Markers
In 3% of cases, there is elevated serum alpha-fetoprotein 6.
Radiographic features
Plain radiograph
Non-specific features such as hepatomegaly and liver calcifications, present in ~15% of cases, may be seen. Indirect signs of congestive heart failure may be present on a chest radiograph.
Ultrasound
Infantile hepatic hemangiomas have a variable sonographic appearance and can be either hypoechoic or hyperechoic or may display mixed echogenicity with prominent vascular channels. Color Doppler sonographic evaluation will show increased flow.
CT
There is typical peripheral enhancement with gradual filling-in. Another characteristic finding is a reduction in the aortic caliber (mid-aortic syndrome) distal to the level of the celiac axis because of the important vascular distribution toward the liver. The same process will cause celiac trunk and hepatic artery hypertrophy.
MRI
Multifocal hemangiomas are spherical lesions with homogeneous signal intensity on MRI. Large flow voids are usually present. Typical signal characteristics include:
T1: hypointense 3
T2: hyperintense 3
They generally demonstrate uniform enhancement and may demonstrate the same vascular changes as seen on CT.
Treatment and prognosis
The natural history of infantile hepatic hemangiomas in infancy is a rapid, proliferative growth phase in the first six months of life, followed by regression and involution.
If the child remains asymptomatic, no treatment may be needed.
If symptoms of high-output cardiac failure occur, the first line of therapy is propranolol. If medical treatment fails, the lesions may be embolized to control any arteriovenous shunting causing cardiac failure.
Differential diagnosis
-
elevated alpha-fetoprotein
not common in neonates
neuroblastoma metastasis: usually multiple
mesenchymal hamartoma (usually seen as multilocular cystic mass) 7,8
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