Hemangioma

A hemangioma is a benign and usually self-involuting tumor (swelling or growth) of the endothelial cells that line blood vessels that is characterised by increased number of normal or abnormal vessels filled with blood. It usually appears in the first weeks of life and grows most rapidly over the first six months. Usually, growth is complete and involution has commenced by twelve months. Half of all infantile hemangiomas have completed involution by age five, 70% by age seven, and most of the remainder by age twelve. In more severe cases hemangiomas may leave residual tissue damage. In infancy, it is the most common tumor. The word "hemangioma" comes from the Greek haema- (αίμα), "blood"; angeio (αγγείο), "vessel"; -oma (-ωμα), "tumor".

Terminology

The terminology used to define, describe and categorize vascular anomalies, abnormal lumps made up of blood vessels, has changed. The term hemangioma originally described any vascular tumor-like structure, whether it was present at or around birth or appeared later in life. Mulliken et al. categorized these conditions into two families: one of self-involuting tumors, growing lesions that eventually disappear, and another of malformations, enlarged or abnormal vessels present at birth and essentially permanent. The importance of this distinction is that it makes it possible for early-in-life differentiation between lesions that will resolve versus those that are permanent. Examples of permanent malformations include port-wine stains (capillary vascular malformation) and masses of abnormal swollen veins (venous malformations). The Mulliken categorisation has received major confirmation following discovery of the Glut-1 marker.