"Keloid Scars" is different from "Hypertrophic Scars". Hypertrophic scars are caused by deeper tissue wounds (such as scars after surgery). Scar tissue appear during the healing process. Collagen overgrowth causes the scar to appear slightly convex, the color becomes darker, but the overgrowth is confined to the original wound, does not extend outward, and the scar have a chance to gradually settle over time.
In contrast, keloid scar is a firm, smooth, hard growth due to spontaneous scar formation. It can arise soon after an injury, or develop months later. Keloids may be uncomfortable or itchy, and may be much larger than the original wound. They may form on any part of the body, although the upper chest and shoulders are especially prone to them.
The precise reason that wound healing sometimes leads to keloid formation is not known yet but can be due to genetic influence. While most people never form keloids, others develop them after minor injuries, burns, insect bites and acne spots. Dark skinned people form keloids more easily than Caucasians.
Intralesional steroid injection can be used to improve hypertrophic scar and keloid scar. Steroid would help to absorb excessive collagen, while inhibiting the production of collagen. Patients need to inject once every three to four weeks for about half a year. It is suitable for patients who do not respond well to silicon gel sheet but may not be suitable if the scar area is too large for injection. This method has a shorter treatment time and is very effective with a success rate of 80%.