What blood disease causes scars to puff up?

The blood disease that can cause scars to puff up is called keloid formation. Keloids are a type of raised scar that occurs due to an overproduction of collagen during the healing process. They often extend beyond the original wound site and can be itchy or painful. While not exclusively a blood disease, certain conditions affecting the blood, like sickle cell disease, can increase the likelihood of keloid formation.