Deep hemangiomas grow within the skin and deep beneath it. They cause the skin to bulge and may be purple or, if they are very deep, flesh-coloured. Most deep hemangiomas grow between 1 inch and 2 inches across, although sometimes they grow much larger. More than half occur on the head and neck. Sometimes, hemangiomas develop in organs, such as the liver. Superficial and deep hemangiomas do not cause pain but occasionally break open (ulcerate) and bleed, which can be difficult to stop. Hemangiomas around the eye may grow large enough to block vision, which can lead to permanent vision loss if uncorrected. Hemangiomas may also block the nose or throat, which can obstruct breathing. Because hemangiomas often go away on their own, doctors do not treat them when they first appear unless they grow rapidly, obstruct vision or breathing, ulcerate, or are cosmetically distressing.