A hemangioma is a noncancerous tumor made of blood vessels. The vessels are lined by endothelial cells, the flat cells that form the inner surface of every blood vessel in the body.
Hemangiomas are common. They can develop almost anywhere, most often in the skin, the head and neck, and the liver. They range from a few millimeters across to more than 20 cm. Most are red to blue and have a clear border separating them from the surrounding tissue.
A hemangioma does not spread to other parts of the body and does not turn into cancer.
This article explains how doctors diagnose a hemangioma, what the type in your report means, and how they manage these tumors.
Doctors who treat blood vessel growths divide them into two groups, and the difference explains why some shrink and others do not.
Some growths are still called hemangiomas out of long habit even though they belong in the second group. The clearest example is the cavernous hemangioma of the liver, brain, or spine, which specialists in this field classify as a malformation. You may see either term used, and your doctor can tell you which applies to you.
Your report will usually name a type. The type depends on when the lesion appeared, where it is, and what the vessels look like under the microscope:
All of these are noncancerous, although they behave differently. Some disappear on their own, and others persist or need treatment.
Symptoms depend on the location, size, and type. Many hemangiomas cause no symptoms and are found during imaging done for another reason.
Doctors often identify many hemangiomas by appearance, and imaging such as ultrasound or MRI is often enough for lesions inside the body. A pathology report is produced when a sample is taken in a biopsy or when the whole lesion is removed.
Under the microscope, a hemangioma is made of blood vessels of varying size lined by a single layer of endothelial cells. The cells look flat and uniform, and the vessels are well formed and separated by normal supporting tissue. Dividing cells are rare or absent.
The size and arrangement of the vessels are what allow a pathologist to name the type. Small packed vessels indicate a capillary hemangioma, and large open spaces indicate a cavernous hemangioma.
Immunohistochemistry is a test that uses antibodies to show which proteins cells make. It is not needed for most hemangiomas. When it is used, your report may include some of the following:
Blood vessel cancers exist, and the most important is angiosarcoma. Under the microscope, a hemangioma is made of well-formed vessels lined by a single layer of flat, uniform cells, and it does not destroy the surrounding tissue.
In an angiosarcoma, the vessels are irregular and poorly formed, the lining cells are crowded and abnormal, and the tumor grows into surrounding tissue. Some noncancerous lesions, such as anastomosing hemangioma, look worrying at first glance, which is why these cases are examined carefully and sometimes reviewed by a second pathologist.
A hemangioma does not turn into an angiosarcoma over time.
Tumor regression means a lesion shrinks on its own, sometimes disappearing completely. It is typical of infantile hemangioma, which usually shrinks over several years during childhood.
Not every hemangioma regresses. Cavernous hemangiomas and most lesions in adults stay the same size or grow slowly, so a lesion that has not changed is behaving as expected.
A margin is the edge of tissue cut by the surgeon. For a hemangioma, a positive margin does not mean what it does for cancer.
It means only that some vessels may remain, which raises the chance the lesion comes back in that spot. This is most common with types that blend into surrounding tissue, such as an intramuscular hemangioma.
The outlook is excellent. A hemangioma is noncancerous, does not spread, and does not become cancer. Many disappear without treatment, and those that are removed rarely come back.
Lesions without a clear border, particularly those inside muscle, come back more often because some abnormal vessels are left behind. A lesion that comes back is still noncancerous.
Not every hemangioma needs treatment. The decision depends on size, location, symptoms, and whether it is expected to shrink on its own.