Hemangioma: Understanding Your Pathology Report

Section Editor: Bibianna Purgina MD FRCPC
September 25, 2026

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.

Hemangiomas and vascular malformations

Doctors who treat blood vessel growths divide them into two groups, and the difference explains why some shrink and others do not.

Vascular tumors. These grow because the cells lining the vessels multiply. Infantile hemangioma is the most common example. Many grow for a period and then shrink.
Vascular malformations. These are blood vessels that formed abnormally before birth. The cells are not multiplying, so these lesions grow in proportion to the person and do not shrink on their own.

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.

What are the types of hemangioma?

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:

Infantile hemangioma. This is the most common type. It appears in the first days or weeks after birth, grows for several months, and then slowly shrinks over years. Most need no treatment.
Congenital hemangioma. This type is fully formed at birth. Some shrink rapidly during infancy, some shrink partly, and some do not shrink at all.
Capillary hemangioma. Made of tightly packed small vessels, which give it a bright red color.
Cavernous hemangioma. Made of large, widened vessels, often deeper in the body such as in the liver, brain, or eye. These do not shrink on their own.
Lobular capillary hemangioma. A fast-growing red bump on the skin or in the mouth that bleeds easily, often linked to injury or pregnancy. It was previously called a pyogenic granuloma, a misleading name because the lesion is neither an infection nor made of the cells that term implies.
Epithelioid hemangioma. Usually develops in the head and neck, sometimes after an injury. Under the microscope, it contains many immune cells called eosinophils. It is also called angiolymphoid hyperplasia with eosinophilia.
Anastomosing hemangioma. An uncommon type found in the kidney, liver, or the tissue around them. Its connected, branching vessels can closely resemble a cancer under the microscope, which is why it is named separately.
Intramuscular hemangioma. Develops inside a muscle, usually in a limb, and often contains fat as well as vessels. Because it blends into the muscle, it can be difficult to remove completely.

All of these are noncancerous, although they behave differently. Some disappear on their own, and others persist or need treatment.

What are the symptoms of a hemangioma?

Symptoms depend on the location, size, and type. Many hemangiomas cause no symptoms and are found during imaging done for another reason.

A visible lump. Most skin hemangiomas appear as a red or blue lump that may grow before settling or shrinking.
Pain or tenderness. This can happen when the lesion is near a nerve or in a sensitive area.
Pressure on nearby structures. A large hemangioma in an organ such as the liver may cause discomfort or affect organ function.
Bleeding. A hemangioma close to the surface can break open and bleed, particularly after an injury.
Appearance. A hemangioma in a visible location can be distressing, and this is a legitimate reason to discuss treatment.

How is the diagnosis made?

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

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:

CD31 and ERG. Endothelial cells make these proteins, confirming that the lesion is made of blood vessels.
GLUT1. This protein is positive in an infantile hemangioma and negative in a congenital hemangioma. It is the main test used to separate the two, which matters because they behave differently.
HHV-8. This viral marker is negative in a hemangioma. A positive result would indicate Kaposi sarcoma instead.

How is a hemangioma different from a cancer?

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.

What does tumor regression mean?

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.

Margins

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.

What is the prognosis?

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.

What happens after the diagnosis?

Not every hemangioma needs treatment. The decision depends on size, location, symptoms, and whether it is expected to shrink on its own.

Observation. Most infantile hemangiomas are monitored, since they shrink over time.
Medication. A beta-blocker called propranolol can shrink an infantile hemangioma and is used when the lesion is large, growing quickly, affecting vision or breathing, or ulcerating.
Surgery. Removal may be recommended for a lesion that does not shrink, that bleeds, that interferes with function, or that is distressing in appearance.
Other treatments. Laser treatment can help some skin lesions. For lesions inside the body, a procedure that blocks the blood supply may be considered.

Questions to ask your doctor

Which type of hemangioma does my report describe?
Is this expected to shrink on its own, or will it stay?
Was the whole lesion removed, and were the margins negative?
Is there a chance it will come back?
Do I need any follow-up or imaging?
Would any treatment help with symptoms or appearance?
For my child, what growth should I expect over the next year?