A benign (not cancer) blood vessel tumor that forms on or under the skin. Spindle cell hemangiomas have cells called spindle cells that look long and slender under a microscope. These tumors are painful red-brown or bluish lesions that usually appear on the arms or legs. One or more lesions may form, and they can sometimes rupture (break open) and bleed. Spindle cell hemangiomas usually occur in young adults but can sometimes occur in children. They are a type of vascular tumor.