Unlike atrophic scars, hypertrophic and keloid scars form as raised lumps of scar tissue where the acne once was. This happens when scar tissue builds up, sometimes from previous acne spots. Hypertrophic scars are the same size as the acne that caused them.

Hypertrophic scars are firm, raised scars that grow above the surface of the skin. Hypertrophic scars caused by acne are most often found on the torso, especially in men, but they can happen anywhere on the body. Hypertrophic scars are more common after a deep wound or trauma.

A hypertrophic scar occurs when excess collagen and fibrinogen build up at the injury site during healing. The resulting hypertrophic scar can be raised, red, uncomfortable, and potentially limit movement.

A hypertrophic scar is the same size as the acne lesion that caused it, while a keloid scar is an excessive scar formation often larger than the causative lesion. They occur more frequently along the jawline, chest, and upper back.

Keloid and hypertrophic scars are common types of scarring that can occur as a result of the acne healing process. They appear as raised lesions of scar tissue on the skin and are a result of the overgrowth of fibrous tissue in the region where the acne lesion had developed.