Infantile hepatic hemangiomas (IHH) are a liver lesion composed of large endothelial-lined vascular channels seen in fetuses and neonates. It should not be confused with a hepatic epithelioid hemangioendothelioma, which occurs in older patients.
Those benign tumors were previously referred 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).
IHH occur in fetuses and neonates and have been detected in utero as early as at 16 weeks of gestation. It is the most frequent liver mass in infants (<6 months).
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.
IHH are histologically similar to hemangiomas (strawberry nevus) but distinct from both adult type cavernous hemangiomas which are venous malformations and angiosarcomas.
In 3% of cases, there is elevated AFP in serum 6.
- hypothyroidism: probably due to high levels of type 3 iodothyronine deiodinase activity produced by hemangiomas 3
- hemangiomata elsewhere in 10% of cases
Non-specific features such as hepatomegaly and liver calcifications, which is present in ~15% of the cases, may be seen. Indirect signs of congestive heart failure may be present on a chest radiograph.
Infantile hepatic hemangiomas have a variable sonographic appearance and may be either hypoechoic or hyperechoic or may have mixed echogenicity with prominent vascular channels. Color Doppler sonographic evaluation will show increased flow.
There is typical peripheral enhancement with gradual filling-in. Another characteristic finding is the 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.
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 IHH 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 then, the lesions may be embolized to control any arteriovenous shunting causing the cardiac failure.
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