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