Vascular Lesion: Definition

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A vascular lesion is an abnormal growth made mostly of blood vessels or the cells that line them. Doctors call these cells endothelial cells. The term covers many different conditions. Some are normal healing responses, some are present from birth, some are noncancerous tumors, and a few are cancers. Vascular lesions can occur anywhere in the body, but they are most common in the skin.

Vascular lesion is a descriptive term, not a diagnosis on its own. A pathologist uses it to describe what is seen under the microscope, and the final diagnosis names the specific type. This article explains the main groups of vascular lesions, how pathologists identify them, and what the groups mean for you.

What are the main types of vascular lesions?

Doctors group vascular lesions by how they form and how they behave. Five groups cover most of the lesions on a pathology report:

Reactive lesions. The body forms these in response to injury, infection, or other tissue changes.
Vascular malformations. These are errors in how vessels formed. They are present at birth.
Benign vascular tumors. These are noncancerous growths of vessels.
Intermediate vascular tumors. These behave between benign and malignant tumors.
Malignant vascular tumors. These are cancers that start from endothelial cells.

What are reactive vascular lesions?

Reactive vascular lesions are noncancerous growths that form as the body responds to a change in the tissue. Reactive changes are not tumors. Examples of reactive vascular lesions include:

Granulation tissue. Granulation tissue is new tissue, rich in small vessels, that fills a wound as it heals. It is a normal part of healing.
Lobular capillary hemangioma. A lobular capillary hemangioma is a common growth of small vessels, often on the skin or inside the mouth. Many doctors view it as an exaggerated healing response. Its older name is pyogenic granuloma.
Stasis dermatitis. This skin change develops when poor blood flow in the legs damages the skin and its vessels.
Bacillary angiomatosis. A rare bacterial infection that causes vessels to multiply in the skin.
Reactive angioendotheliomatosis. In this rare condition, endothelial cells multiply inside small skin vessels in response to another illness.

What are vascular malformations?

Vascular malformations are errors in the way blood or lymphatic vessels formed before birth. The International Society for the Study of Vascular Anomalies (ISSVA) classification keeps malformations separate from tumors. Malformations are not true tumors. They are present at birth, but people may not notice them until later in life. All are noncancerous. The main types are:

Capillary malformation. This malformation involves the smallest vessels in the skin. A port-wine stain is the best-known example.
Venous malformation. This malformation involves veins. It often looks blue and soft.
Lymphatic malformation. This malformation involves the vessels that carry lymph fluid.
Arteriovenous malformation. An arteriovenous malformation (AVM) is a tangle of arteries and veins with a direct connection between them.

What are benign vascular tumors?

A benign vascular tumor is a noncancerous growth made of new blood vessels. It does not spread to other parts of the body. Its symptoms depend on its size and location. The most common type is the hemangioma. Hemangiomas can be present at birth or appear in early childhood. Infantile hemangiomas often shrink on their own as a child grows. Other benign vascular tumors include epithelioid hemangioma, spindle cell hemangioma, and tufted angioma.

Some growths grow around vessels but are not vascular tumors. One example is a perivascular epithelioid cell tumor (PEComa). The World Health Organization (WHO) classifies it in a different group.

What are intermediate vascular tumors?

Intermediate vascular tumors are neither benign nor fully malignant. The WHO classification of soft tissue and bone tumors (5th edition, 2020) splits them into two groups. Locally invasive tumors, which the WHO calls locally aggressive, invade nearby tissue but do not spread to distant sites. Rarely metastasizing tumors can spread, but they seldom do. Examples include:

Kaposiform hemangioendothelioma. This locally invasive tumor mostly affects infants and children. It can cause the Kasabach-Merritt phenomenon, a condition in which platelet counts fall and bleeding risk rises.
Retiform hemangioendothelioma. The WHO classifies this tumor as rarely metastasizing. It often comes back at the same site after removal.
Kaposi sarcoma. The WHO classification (5th edition, 2020) places Kaposi sarcoma in the rarely metastasizing group. A virus called human herpesvirus 8 (HHV-8) causes it. It often occurs in people with a weakened immune system.

What are malignant vascular tumors?

Malignant vascular tumors are cancers that start from endothelial cells. Doctors group them with the sarcomas, the cancers of connective tissue. They can invade nearby tissue and spread to other organs. The two main types are:

Angiosarcoma. Angiosarcoma is a cancer of the cells that line blood or lymphatic vessels. It can occur in many parts of the body, including the skin.
Epithelioid hemangioendothelioma. Epithelioid hemangioendothelioma is a rare cancer whose cells look like epithelioid cells. Despite the name, it starts from endothelial cells, not epithelial cells.

How is a vascular lesion identified?

The pathologist identifies a vascular lesion by studying a tissue sample under the microscope. The sample comes from a biopsy or from surgical removal of the lesion. The pathologist examines the vessels and the cells that line them. The pathologist also checks how the lesion invades the surrounding tissue. Cancer cells often look more abnormal and tend to invade nearby tissue.

The pathologist may add immunohistochemistry. This test uses antibodies to mark specific proteins in the cells. Common stains include:

Endothelial markers. CD31, CD34, and ERG confirm that the cells are endothelial cells.
Lymphatic marker. D2-40 marks lymphatic vessels.
GLUT1. GLUT1 helps identify infantile hemangioma.
HHV-8. A stain for HHV-8 helps confirm Kaposi sarcoma.

Are vascular lesions cancer?

Most vascular lesions are not cancer. Reactive lesions, malformations, and benign tumors are all noncancerous, and they are much more common than the malignant tumors. Intermediate tumors fall in between, and malignant tumors are cancers. The specific diagnosis on your report tells you which group applies. The term vascular lesion alone does not.

What happens after a vascular lesion is identified?

The next steps depend on the diagnosis. Some lesions need no treatment and the care team watches them over time. Surgeons remove others. A specialist team manages intermediate and malignant tumors. Your doctor can explain which option applies to your lesion and why.

Questions to ask your doctor

What is the specific diagnosis of my vascular lesion?
Is my lesion reactive, a malformation, or a tumor?
Is my lesion benign, intermediate, or malignant?
Were any stains done to identify the type of lesion?
Was the lesion completely removed?
Could the lesion come back after treatment?
Does my lesion need treatment, or can it be watched?
What follow-up will I need?