Keloids are raised scars that can occur wherever there is skin injury, but usually form on earlobes, shoulders, cheeks, or the chest. The exact cause of keloids is not fully understood, but most experts agree that it is likely a dysfunction of the wound-healing process. Collagen, a protein found throughout the body, is useful to wound healing, but when the body produces too much, keloids can form. Keloid growth might be triggered by any sort of skin injury, including an insect bite, acne, an injection, body piercing, burns, hair removal, and even minor scratches and bumps. Sometimes keloids form for no obvious reason. Risk factors for keloids include having brown or Black skin, having a personal or family history of keloids, and being under 30 years old. Keloids are generally harmless, but they can be itchy, painful, or tender to the touch. If you are prone to developing keloids, it is recommended to avoid getting tattoos and piercings.