Differences in collagen architecture between keloid, hypertrophic scar, normotrophic scar, and normal skin: An objective histopathological analysis

TLDR

Scarring can result in normotrophic, hypertrophic, or keloidal forms, each requiring distinct treatment strategies. The study aims to distinguish these scar types through histopathological analysis. Collagen orientation and bundle thickness were quantified in 25 normal skin, 57 normotrophic, 56 hypertrophic, and 56 keloid biopsies using fast Fourier transform to compute an orientation index (0–1) and bundle distance. Scars exhibited a higher orientation index than normal skin, indicating more parallel collagen, while keloids had a significantly larger bundle distance, revealing thicker collagen bundles; no orientation differences were observed among scar types.

Abstract

ABSTRACT Normotrophic, hypertrophic, and keloidal scars are different types of scar formation, which all need a different approach in treatment. Therefore, it is important to differentiate between these types of scar, not only clinically but also histopathologically. Differences were explored for collagen orientation and bundle thickness in 25 normal skin, 57 normotrophic scar, 56 hypertrophic scar, and 56 keloid biopsies, which were selected on clinical diagnosis. Image analysis was performed by fast fourier transformation. The calculated collagen orientation index ranged from 0 (random orientation) to 1 (parallel orientation). The bundle distance was calculated by the average distance between the centers of the collagen bundles. The results showed that compared with all three types of scars, the collagen orientation index was significantly lower in normal skin, which indicates that scars are organized in a more parallel manner. No differences were found between the different scars. Secondly, compared with normal skin, normotrophic scar, and hypertrophic scar, the bundle distance was significantly larger in keloidal scar, which suggests that thicker collagen bundles are present in keloidal scar. This first extensive histological study showed objective differences between normal skin, normotrophic, hypertrophic, and keloidal scar.