Definition hemangiomas

Hemangiomas are vascular lesions that are not usually present at birth; proliferate during the first years of life and then involute.

A hemangioma is a benign vascular tumor exhibiting unique characteristics in terms of its clinical course and natural history. In early stages, it is composed of endothelial cells. The cells proliferate and make numerous newly formed vessels rapidly. The process of cell proliferation and vessel formation continues throughout the first year of the patient’s life. This is the period that an enlargement of the lesion is evident.
By the end of the first year, the growth phase is completed and then the involution phase begins. This is a much longer process. Eventually the affected area will be completely restructured and all the previously formed vessels will be transformed to fibro fatty tissue. This period is marked by a significant reduction of the lesion’s size.

Hemangiomas are the most common birthmark of infancy. They are benign (not a cancer) stem cell tumors with no genetic or causative factor. Hemangiomas occur in infants only; they never develop in adults.
While not well understood, hemangiomas affect girls three to five times more often than boys. Other associated risk factors include prematurity, low birth weight, and twin pregnancy. While hemangiomas can appear anywhere on the body, more than 80% involve the head and neck, including areas around the mouth, eyes, tip of the nose and cheek.

Recent evidence suggests that hemangiomas are stem cell tumors. They are however benign in their behavior. They grow for a period of time and do not spread to other tissues. Most are quite small and innocuous but some can be quite large. At present, there are no known statistics as to what percentage will be problematic.