Local, Systemic, and Genetic Risk Factors for Keloids and Hypertrophic Scars and the Reset Concept of Pathological Scar Therapy

  • Rei OgawaEmail author


Keloids and hypertrophic scars are red and elevated pathological inflammatory scars that are caused by aberrant wound healing after injury or irritation to the reticular dermis. These injuries include trauma, insect bite, burn, surgery, vaccination, skin piercing, acne, folliculitis, chicken pox, and herpes zoster. The importance of the reticular dermis in this pathology is demonstrated by the fact that superficial injuries that do not reach the reticular dermis will never cause keloidal or hypertrophic scarring. The aberrant wound healing of these pathological scars is characterized by continuous inflammation that is mainly found in the reticular dermis. Thus, the reticular layer of these scars contains large numbers of inflammatory cells, fibroblasts, and newly formed blood vessels along with accumulations of collagen. Increasing evidence suggests that these characteristic histological features of keloids and hypertrophic scars are driven by external and/or internal stimuli that are placed on the reticular layer during the course of wound healing. These stimuli are either delivered repeatedly or are continuously present. This prolongs and amplifies the reticular dermal inflammation, thereby preventing the orderly progression of wound healing to the maturation phase. These external and internal stimuli include multiple local, systemic, and genetic factors. The nature, strength, and duration of these stimuli ultimately shape the characteristics, quantity, and progression of keloids and hypertrophic scars. Therapies should aim to extinguish the inflammation. In severe cases, surgery followed by radiotherapy and then conservative therapies will be needed to fully eliminate the inflammation and prevent recurrence: this approach resets the skin to a state that allows scar maturation (the “Reset Concept”). At that point, aesthetic and functional reconstruction can proceed.


Keloid Hypertrophic scar Tension Mechanical force Hypertension High blood pressure Estrogen Sex hormone Dermis 


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© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  1. 1.Department of Plastic, Reconstructive and Aesthetic SurgeryNippon Medical SchoolTokyoJapan

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