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An extremely common benign tumor, occurring most commonly in infancy and childhood, made up of newly formed blood vessels, and resulting from malformation of angioblastic tissue of fetal life. It can occur anywhere in the body but is most frequently noticed in the skin and subcutaneous tissues. About 75% are present at birth, and about 60% occur in the head and neck area. The majority in infancy will regress spontaneously. Some hemangiomas grow rapidly during the early months of life and may be a source of some concern, although virtually all disappear by about 5 years of age. They do not metastasize and simple excision will often be curative. (Dorland, 27th ed; from Stedman, 25th ed; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1355)