A 35-year-old woman develops a raised, pruritic, erythematous scar that remains confined to the original wound boundaries after a Caesarean section. This is best classified as a hypertrophic scar. How does it differ pathologically from a keloid?
- A Hypertrophic scars remain within wound boundaries, regress over time, and have whorled collagen type I bundles; keloids extend beyond the wound, rarely regress, have disorganised thick type I collagen, and are more common in dark-skinned individuals ✓
- B Hypertrophic scars contain myofibroblasts; keloids do not
- C Keloids are pre-malignant and require excision biopsy; hypertrophic scars are malignant
- D Both are caused by excess type III collagen; the only difference is anatomical site
Correct answer: A. Hypertrophic scars remain within wound boundaries, regress over time, and have whorled collagen type I bundles; keloids extend beyond the wound, rarely regress, have disorganised thick type I collagen, and are more common in dark-skinned individuals
Explanation
Hypertrophic scars stay within the original wound boundaries, are composed of whorled type I collagen bundles, contain excess myofibroblasts, and typically regress spontaneously over 1–2 years. Keloids extend beyond the wound margins (claw-like projections), contain thick disorganised type I collagen bundles, rarely regress, and have a strong racial predilection (darkly pigmented skin, especially Black and Asian individuals). Keloids are not pre-malignant. Both scars contain type I collagen (not type III which predominates in early healing).
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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