What is it?
Hemangioma is the most common benign tumor of the liver and has a prevalence in the population of 5% to 20%. The incidence is higher in women (men:women = 4:1), and the average age of diagnosis is approximately 40 years.
Small nodules of capillary hemangioma do not have clinical significance, while voluminous cavernous hemangiomas are more often the reason for surgical intervention. Cavernous angiomas, along with focal nodular hyperplasia, are considered congenital vascular malformations; in fact, the possible increase in the size of the lesions is more associated with progressive ectasia (i.e., dilation) of the vessels, rather than with cell proliferation. Usually these are single formations less than 5 cm in size, located with the same frequency in the right or left lobe of the liver.
Lesions larger than 5 cm in diameter are commonly referred to as “giant hemangiomas (or angiomas)”. Fibrous involution or angioma thrombosis can lead to formation of dense fibrous masses, which are often difficult to distinguish from other lesions. From a histological point of view, these are lesions formed by an area of vessels bounded by the endothelium and separated by fibrous tissue.
Liver angiomas in children are very common and account for about 12% of cases of liver cancer in children. They are usually multi-focal and can affect other organs. If the hemangioma is large, the child may show signs of heart failure due to the presence of arteriovenous shunts (i.e., abnormal connections), and in these cases, treatment (radiological or surgical) is recommended. Small capillary angiomas usually regress spontaneously.
Which are the symptoms?
In most patients, symptoms may be absent, and angiomas are detected accidentally, although the presence of bulk masses may cause non-specific abdominal complaints in the upper abdomen. In symptomatic patients, it is always necessary to exclude the presence of other pathologies underlying the complaints.
Rapid increase in the size or thrombosis of the lesion are cases that can lead to sudden appearance of symptoms. Spontaneous rapture of an angioma is quite rare; a clinical syndrome characterized by thrombocytopenia (i.e., a decrease in the number of platelets) and consumption coagulopathy (i.e., blood clotting disorders), which is called Kazabach-Meritt syndrome, is also rare.
Liver function tests and serum α-fetoprotein levels are usually normal.
How is it diagnosed?
To make an accurate diagnosis, conventional radiological examinations (ultrasound, CT, and MRI) are usually sufficient. Percutaneous biopsy (i.e., taking a small amount of tissue with a thin needle) when angioma is suspected is a potentially dangerous and inaccurate procedure and therefore is not recommended.
On ultrasound, angiomas are hyperechogenic and well delineated. On CT, they are visualized as well-defined, hypodensated lesions with lobed edges with a characteristic enhancement (i.e., capture of the contrast) after administration of a contrast agent that spreads from the periphery to the center (sensitivity of 75-85% and specificity of 75-100%). The diagnostic accuracy in MRI is high as well (sensitivity of 95% and specificity of 100%).
Although the natural history of angiomas (i.e., the evolution of neoplasms in the absence of treatment) is not well documented, most neoplasms remain stable over time with a very low risk of rupture or bleeding. However, sometimes there is an increase in the size of the tumor and the appearance of symptoms, so the patient needs to be examined for further surgical intervention. There have never been any cases of malignant degeneration of angioma.
How is it treated?
Proper treatment of angimatous formations requires that, after diagnosis and absence of symptoms, the patient is sent for periodic observation (i.e., for evaluation of instrumental examinations at regular intervals). Patients with symptoms should be further examined to rule out the presence of other pathologies and, most likely, be referred to surgical removal of the formation, if no other causes of complaints of symptoms are identified. The rupture of the lesion, the increase in size, and the Kazabach-Meritt syndrome are indications for surgical intervention. In rare cases of diagnostic uncertainty, resection of the neoplasm may be required to obtain the definite diagnosis. Surgical resection usually involves enucleating the formation by checking the blood supply to the arteries, but sometimes anatomical resection may be required.
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