HEMANGIOMAS are congenital abnormalities rather than true tumors and most of them are present before birth. Hemangioma of bone is comparatively rare and usually affects the vertebrae, skull, and long bones. It may occur at any age and is equally distributed between the sexes. The common histologic types are: (a) capillary hemangioma, consisting of small vessels and capillaries separated by connective-tissue stroma, and (b) cavernous hemangioma, consisting of large thin-walled vessels and sinuses lined by endothelium and containing blood, with a delicate connective-tissue stroma. Angiosarcomatous tissue has also been found in bone. Thomas (1942), in an excellent article on vascular tumors of bone, stated that they are mesenchymal in origin probably growing from embryonal remnants by a process of endothelial proliferation and differentiation into blood vessels. They are usually benign and may undergo regression and heal. True malignant angiomas also exist and are characterized by rapid growth, invasion of s...