Vascular Anomalies Center | What are Vascular Anomalies?

Vascular anomalies are composed of blood vessels that have developed abnormally. These blood vessels include arteries, veins, lymphatic vessels and/or capillaries. 

Boston Children's Hospital's Vascular Anomalies Center classifies vascular anomalies into two categories:

  • vascular malformations
  • vascular tumors
Both categories refer to a variety of non-cancerous birthmarks and lesions. Although lesions in these two groups can often look quite similar, they are biologically very different and, therefore, require different treatment.

How vascular anomalies manifest themselves can vary greatly from patient to patient, from single "stand-alone" anomalies to complex conditions or syndromes that combine more than one anomaly or affect multiple parts of the body.

Vascular malformations

  • Vascular malformations are benign (non-cancerous) lesions.
  • They are present at birth, but may not become visible for weeks or months.
  • Unlike hemangiomas, vascular malformations do not have a growth cycle and tend to grow slowly throughout a child's life.
  • Vascular malformations are usually sporadic (occurring by chance), although some are inherited within families.
  • There are several types of vascular malformations:
    • Capillary (port wine stains) are always present at birth as pink or purple skin patches.
    • Venous malformations are often confused with hemangiomas. They are soft to the touch and the color disappears when compressed. They are most commonly found on the jaw, cheek, tongue and lips.
    • Lymphatic malformations form when excess fluid accumulates within the lymphatic vessels.
    • Arteriovenous malformations are caused by abnormal connections between arteries and veins, resulting in high flow, pulsating collections of blood vessels.
    • Mixed malformations are combinations of any of the other four types.

Vascular tumors

  • These rare benign (noncancerous) tumors are formed of blood vessels that grow abnormally.
  • They may grow but do not spread to other parts of the body; they are not cancers.
  • Includes hemangiomas, the most common kind of vascular anomaly.
  • Some shrink (or involute) on their own over time, while others may require treatment.
  • When they appear depends on the tumor. For instance hemangiomas appear within the first few weeks of a child's life, while epitheliod hemangioendotheliomas tend to appear in older teens and adults.
  • Vascular tumors are formed by unusually dense groups of endothelial cells, which normally line the blood vessels.
  • While the causes of the different vascular tumors are not known, they are generally sporadic.

Learn more about the vascular anomalies we treat.