Hypertrophic scars and keloids, both generate excessive scar tissue, yet keloids are characterized by their extensive growth beyond the borders of the original wound which is not observed in hypertrophic scars. Whether or not hypertrophic scars and keloids are distinct entities, remains obscure.

The goal of a study published in Experimental Dermatology was to summarize and evaluate all publications in which both, hypertrophic scars and keloids were studied and compared to one another within the same study.

The findings of this review revealed that horizontal growth is the mainstay of the keloid diagnosis and remains the strongest argument in support of keloids and hypertrophic scars being distinct entities—the histopathological distinction is less straightforward. Although keloidal collagen remains the strongest keloid parameter, dermal nodules and α-SMA-immunoreactivity are not limited to hypertrophic scars alone.

It was concluded that the current hypertrophic scars-keloid differences are mostly quantitative in nature rather than qualitative, and many similar abnormalities exist in both lesions. Nonetheless, the presence of similarities does not equate the absence of fundamental differences – some of which may not yet have been uncovered given how much we still have to learn about the processes involved in normal wound healing. Hence, hypertrophic scars and keloids should be treated as separate entities, unless newer findings indicate otherwise.

Source: Experimental Dermatology. 2020 Jun 1. doi: 10.1111/exd.14121.