From the Guidelines
Keloid formation is primarily driven by abnormal wound healing, where excessive collagen production continues beyond normal scar formation, triggered by tissue injury and dysregulation of growth factors like TGF-β, PDGF, and IGF-1. The pathophysiology of keloid formation begins with tissue injury, which triggers the standard wound healing cascade, but in keloid formation, this process becomes dysregulated. After injury, inflammatory cells release cytokines and growth factors that stimulate fibroblast proliferation and collagen synthesis. In keloids, fibroblasts demonstrate heightened sensitivity to these signals and continue producing collagen long after wound closure should have occurred.
Some key factors that contribute to keloid formation include:
- Genetic factors, as keloids show familial tendencies and are more common in individuals with darker skin 1
- Mechanical tension across wounds, which explains their frequent occurrence over high-tension areas like the chest, shoulders, and earlobes
- Imbalance between collagen production and degradation, with reduced activity of matrix metalloproteinases (MMPs) that would normally break down excess collagen
Understanding this pathophysiology helps explain why keloids extend beyond the original wound boundaries and why they frequently recur after surgical excision. Prevention is the best strategy for managing keloids, especially in individuals with a history of keloid formation or a family history of keloids. According to recent studies, individuals with a personal or family history of keloids should be cautioned about the risk associated with scarification and other body modification processes 1.
The most recent and highest quality study on this topic is from 2017, which highlights the importance of prevention and cautious approach to body modifications in individuals with a history of keloids 1. In summary, keloid formation is a complex process involving abnormal wound healing, genetic factors, and mechanical tension, and prevention is key to managing this condition.
From the Research
Pathophysiology of Keloid Formation
The pathophysiology behind keloid formation is complex and involves an abnormal wound-healing process. Key factors include:
- Excessive production of extracellular matrix (ECM) components, particularly collagen, leading to a disorganized fibroproliferative collagen response 2, 3, 4
- Lack of control mechanisms self-regulating cell proliferation and tissue repair, resulting in the formation of nodular lesions that extend beyond the area of injury 5
- Excessive expression of growth factors and cytokines, contributing to the development of keloids 3
Abnormal Wound-Healing Process
The abnormal wound-healing process underlying keloid formation is characterized by:
- A disorganized extracellular matrix due to excessive fibroproliferative collagen response 2, 4
- Uncontrolled cell proliferation and tissue repair, leading to the growth of keloids beyond the original wound margins 5
- The formation of fibroproliferative dermal tumors with effusive accumulation of ECM components, particularly collagen 3
Genetic and Environmental Factors
Keloid formation is also influenced by: