Correct Answer: A. A keloid scar forms due to increase in the level of growth factors
Keloid formation is fundamentally a disorder of wound healing characterized by excessive collagen deposition driven by elevated growth factors, particularly TGF-β (transforming growth factor-beta), PDGF (platelet-derived growth factor), and FGF (fibroblast growth factor). These growth factors stimulate fibroblast proliferation and collagen synthesis beyond the normal wound-healing phase. The pathophysiology involves dysregulation of the inflammatory response and abnormal fibroblast behavior—keloid fibroblasts show increased proliferation, enhanced collagen production, and reduced apoptosis compared to normal fibroblasts. This results in continuous, excessive accumulation of type I and III collagen in the dermis and subcutaneous tissue. The condition is more prevalent in darker-skinned populations (African, Asian, and Indian populations), with an incidence of 4.5–15% in Indians compared to 0.09% in Caucasians. Growth factors are the primary driver of this pathologic fibrosis, making option A the correct statement. Understanding this mechanism is critical for therapeutic approaches targeting growth factor inhibition (e.g., intralesional corticosteroids, TGF-β antagonists) rather than simple surgical excision alone.
Why the other options are wrong
B. The extent does not cross the wound margins — This statement describes a hypertrophic scar, not a keloid. The defining characteristic of a keloid is that it extends beyond the original wound boundaries into surrounding normal skin. This is the key clinical distinction: hypertrophic scars remain confined within the wound margins, while keloids transgress them. This is a common NBE trap—confusing the two entities based on boundary behavior. C. Histopathology of a keloid scar shows reduced collagen and increased vascularity — This is factually incorrect. Keloid histopathology shows increased collagen (not reduced), organized in thick, hyalinized bundles with normal or decreased vascularity (not increased). The excessive collagen deposition is the hallmark microscopic finding. Hypertrophic scars, by contrast, show organized collagen in the direction of skin tension. This option reverses the pathologic findings to mislead students. D. Wide excision of the keloid scar prevents recurrence — Wide excision alone has a high recurrence rate (45–80%) in keloids, particularly in Indian populations with darker skin. Surgical excision without adjuvant therapy (intralesional corticosteroids, radiotherapy, silicone gel, pressure garments) is ineffective and often worsens the condition. This option represents a common clinical misconception—surgery alone is not curative for keloids and may trigger further growth.
High-Yield Facts
- TGF-β, PDGF, and FGF are the primary growth factors driving keloid fibroblast proliferation and collagen synthesis.
- Keloids extend beyond wound margins into normal skin; hypertrophic scars remain confined within wound boundaries—this is the key clinical distinction.
- Incidence in Indians is 4.5–15% compared to 0.09% in Caucasians; darker skin phenotype is a major risk factor.
- Histology shows increased, hyalinized collagen in thick bundles with normal/decreased vascularity, not reduced collagen.
- Surgical excision alone has 45–80% recurrence; adjuvant therapy (intralesional steroids, radiotherapy, pressure) is mandatory for keloid management.
- Keloid fibroblasts show reduced apoptosis and increased proliferation compared to normal fibroblasts—a fundamental cellular abnormality.
Mnemonics
KELOID vs HYPERTROPHIC (Boundary Rule) Keloid = Krosses boundaries (extends beyond wound). Hypertrophic = Honors boundaries (stays within wound). Use this when comparing the two at the bedside. Growth Factors in Keloid (TGF-PDGF-FGF) Transforming, Platelet-derived, Fibroblast growth factors drive keloid formation. Remember: all three promote fibroblast proliferation and collagen synthesis.
NBE Trap
NBE pairs "wide excision prevents recurrence" with keloids to trap students who assume surgical treatment alone is curative. In reality, keloids require multimodal therapy; excision without adjuvants has 45–80% recurrence, especially in Indian populations.
Clinical Pearl
In Indian dermatology and plastic surgery practice, keloids are a major cosmetic and functional problem, particularly after ear piercing, vaccination, or minor trauma in darker-skinned patients. A patient presenting with a scar extending beyond the original wound boundary should immediately raise suspicion for keloid, not hypertrophic scar—this distinction determines whether you offer surgery (contraindicated alone) or intralesional corticosteroids + pressure therapy as first-line management.
_Reference: Bailey & Love Ch. 7 (Wound Healing & Scars); Robbins Ch. 3 (Inflammation & Repair)_