Hypertrophic response and keloid diathesis: two very different forms of scar.
OBJECTIVE
After studying this article, the participant should be able to: 1. Have a greater appreciation of the extent of differences and similarities between keloid and hypertrophic scarring. 2. Have a greater appreciation of the significance of the stage of maturation of a keloid or hypertrophic scar with regard to its morphologic, biochemical, and molecular profile. 3. More critically review basic science research that is based on poorly characterized scar tissue. 4. More critically review clinical studies that are based on poorly characterized scar tissue.


BACKGROUND
Hypertrophic and keloid scars remain extremely challenging, particularly in their variable response to treatment. The understanding of hypertrophic and keloid scarring is evolving from a position where they were regarded as different stages of the same process to the contemporary perspective of two separate entities. This article reviews the differences in the two forms of scarring and discusses the implications for future research.


METHODS
The authors conducted a MEDLINE search of all English language reviews linking key words "hypertrophic," "keloid," and "scarring."


RESULTS
Over the past four decades, there has been considerable clinical and experimental research looking at the biological nature and therapeutic response of keloid and hypertrophic scarring. As more differences are emerging regarding the fundamental biology of the scars, investigators are giving more detailed characterization of their source material. It is evident that even within the broad categories of hypertrophic and keloid scarring there is a heterogenous distribution of pathologic connective tissue matrix biology.


CONCLUSIONS
Considerable advances have been made in our understanding of the fundamental biology of scarring. As research methodology becomes even more sophisticated, it will be even more crucial to extensively characterize source material, recognizing major differences not only between keloid and hypertrophic scar but also between scars of varying stages of maturation and histomorphological, biochemical, and molecular variations within individual scars.
Burd
Andrew
A
Division of Plastic and Reconstructive Surgery, Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. andrewburd@surgery.cuhk.edu.hk
Huang
Lin
L
D017209:Apoptosis / Q000502:physiology; D017439:Cicatrix, Hypertrophic / Q000473:pathology*; D005109:Extracellular Matrix / Q000473:pathology; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007627:Keloid / Q000473:pathology*; D015603:Keratinocytes / Q000378:metabolism; D008833:Microcirculation; D011110:Polymorphism, Genetic; D016212:Transforming Growth Factor beta / Q000378:metabolism
D016212:Transforming Growth Factor beta