Hepatic hemangioma, also known as cavernous hemangioma or simply liver angioma, is the most common benign hepatic tumour. The vast majority of hepatic hemangiomas do not cause symptoms and their practical significance lies in the need to distinguish them from other lesions which may require specific treatment, like for example hepatic carcinoma and hepatic adenoma.
Hemangiomas are widespread in the general population. It is estimated that they are prevalent in between 0.4 and 20% of people. The prognosis is excellent for the great majority of cases. Only large hemangiomas (larger than 5 cm) have the potential to cause symptoms or complications. They can be diagnosed at any age, though it is most common for them to be discovered by chance when analyzing images and scans for other reasons in people between 30 and 50 years.
Pathogenesis
Hemangiomas are benign lesions whose cause is not completely understood. They are considered congenital vascular malformations (hamartomas) which grow by ectasis and not through hyperplasia or hypertrophy.
Their growth has been associated with hormonal factors (estrogens) based on reports of growth during pregnancy. However, estrogen receptors have not been found in any hemangiomas and there can also be growth in post-menopausal women.
Clinical presentation
As indicated, hemangiomas usually have no symptoms and are an incidental discovery in ultrasound or abdominal CT scan. It is very improbable that any hemangioma smaller than 4-5 cm will cause any symptoms.
When there are symptoms, these most frequently comprise pain or discomfort in the upper left side of the abdomen. It is difficult to be specific about the link between abdominal pain with hemangiomas, given that in some studies in more than half of patients the pain has a different explanation to the hemangioma, the most common being irritable bowel syndrome. There can also be nausea, early fullness and a mass sensation. Occasionally the patient presents with acute abdominal pain due to thrombosis or bleeding of the hemangioma.
The Kasabach-Merritt syndrome consists of very large hepatic hemangiomas in children shown as coagulopathy (thrombocytopenia, hypofibrinogenemia and hemolysis). It is probably a different type to the usual cavernous hepatic hemangioma, given that it has been associated with a rare variety of hemangioendothelioma.
Natural history
Follow up studies show that over 80% of hepatic hemangiomas maintain their size over time. Only 1% increase in size and spontaneous rupture is an exceptional occurrence, appearing to be limited to certain larger hemangiomas (bigger than 5 cm) located peripherally.
Diagnosis
Hemangiomas present fairly indicative characteristics on imaging findings:
- Ultrasound: The characteristic ultrasound appearance of hemangiomas is that of an hyperechogenic lesion. However there are exceptions. In cases of fatty liver, the hemangioma can be hypoechogenic with respect to the parenchyma which surrounds it. Lesions larger than 5 cm usually have hypoechogenic areas which represent haemorrhagic areas or fibrosis within the tumour. In patients who are asymptomatic, without cirrhosis and with normal alpha-fetoprotein, a lesion demonstrated by ultrasound as smaller than 4 cm may require no further investigation.
- CT Scan: shows a hypodense mass, occasionally with calcification in the sections without contrast. In the triphasic CT scan, in which images are obtained quickly following the injection of contrast medium, a pattern is observed typical of peripheral impregnation of the tumour where the contrast moves progressively towards the centre.
- MRI Scan: The hemangioma typically has a hypointense aspect in T1 and hyperintense in T2. The use of contrast with gadolinium results in a pattern of impregnation similar to that produced by CT scanning.
- Nuclear Medicine: The schintograph with red blood cells marked with single photon emission computer tomography (SPECT) can be used as a complementary investigation in case of doubt. However, with current dynamic images produced by CT scanning and resonance, this is required less and less.
- Angiography: This is now practically obsolete as a technical diagnostic test for hemangioma.
The fine needle biopsy is generally not recommended when a hepatic hemangioma is suspected because it is not highly productive in terms of diagnosis, and also because of the risk of haemorrhage.
Treatment
The vast majority of hepatic hemangiomas do not require specific treatment. Lesions larger than 5 cm are generally followed up by carrying out imaging to monitor whether the lesion has increased in size. When these lesions are asymptomatic surgical resection to avoid an eventual risk of rupture or haemorrhage is not recommended, given that this risk is very low.
In the rare cases of patients who present with pain or symptoms of extrinsic compression, they must be evaluated with a view to carrying out resection. However, evaluation of the symptoms must be very careful, given that in many cases the pain does not originate from the hemangioma. In one report, 5% of patients who had resections had pain after surgery, confirming that the pain had another cause (frequently irritable bowel syndrome).
In terms of surgical treatment, this may consist of hepatic resection or enucleation. Liver transplant is an alternative for certain very large hemangiomas.
There exist non-surgical treatments which include embolisation, radiotherapy and the use of Interferon. However, there is less experience with these techniques and their effectiveness is limited.
Pregnancy and the use of estrogens are controversial in hemangioma. Pregnancy appears to be safe in cases where hemangiomas are smaller than 10 cm.
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