Which feature best distinguishes a hypertrophic scar from a keloid in wound healing?

Explanation

## Distinguishing Hypertrophic Scars from Keloids ### Clinical Boundary Definition **Key Point:** The most reliable discriminator between hypertrophic scars and keloids is the spatial relationship to the original wound boundary. | Feature | Hypertrophic Scar | Keloid | |---------|-------------------|--------| | **Boundary** | Confined within original wound margins | Extends beyond original wound boundaries | | **Onset** | Appears within weeks to months | May appear months to years after injury | | **Regression** | Often regresses spontaneously over 1–2 years | Rarely regresses; persists indefinitely | | **Genetics** | Less ethnically predisposed | Increased in darker skin types (African, Asian) | | **Symptoms** | May be pruritic or tender | Often pruritic, painful, or symptomatic | | **Histology** | Organized collagen bundles parallel to skin surface | Haphazard, whorled collagen; extends into dermis | | **Treatment Response** | Moderate response to steroids and pressure | Variable; often resistant to conservative therapy | ### Pathophysiologic Basis **High-Yield:** Hypertrophic scars represent an exaggerated but self-limited fibroproliferative response that respects anatomic boundaries. Keloids reflect a pathologic, autonomous fibroblast proliferation that breaches the original wound margin—a hallmark of abnormal wound healing. ### Clinical Pearl A simple bedside rule: if the raised scar tissue stays *within* the scar line, it is hypertrophic; if it *spills over* into normal skin, it is a keloid. This distinction is crucial because keloids are much more difficult to treat and have a higher recurrence rate after excision (45–50%). ### Mnemonic **HYPER = Hypertrophic = Hemmed in (within boundaries)** **KELO = Keloid = Knows no limits (extends beyond)**