Hypertrophic Scars vs Keloids: Key Differences and Treatment
Clinical Distinction
The fundamental difference is that keloids grow beyond the original wound boundaries with horizontal extension into surrounding normal skin, while hypertrophic scars remain confined within the original injury site. 1
Defining Characteristics
Keloids:
- Extend beyond the borders of the original wound with horizontal growth into normal tissue 1
- Can develop from minor trauma (acne, ear piercing) or severe injuries 2
- Higher recurrence rates after excision alone (45-100%) 3
- More resistant to treatment 4
Hypertrophic Scars:
- Remain within the boundaries of the original wound 1
- Result from excessive collagen deposition without horizontal spread 5
- Better response to conservative therapies 4
- Lower recurrence rates with appropriate treatment 3
Histopathological Features
Both conditions show excessive collagen deposition and increased glycosaminoglycan content with elevated collagen turnover 3. Keloidal collagen patterns are the strongest histological marker for keloids, though dermal nodules and α-SMA immunoreactivity are not exclusive to hypertrophic scars 1. The histopathological distinction is less straightforward than clinical appearance, with differences being more quantitative than qualitative 1.
Treatment Approach
First-Line Therapy for Both Conditions
Intralesional triamcinolone acetonide (10-40 mg/mL) is the primary treatment, with 40 mg/mL concentrations recommended for both hypertrophic scars and keloids. 6 This works by decreasing connective tissue components and reducing scar volume 3. Post-operative steroid injections reduce keloid recurrence to less than 50% 3.
Monitor for local adverse effects including atrophy, pigmentary changes, telangiectasias, and hypertrichosis, as well as systemic absorption with repeated injections. 6
Additional Conservative Therapies
Silicone-based occlusive dressings provide benefit through occlusion and hydration rather than the silicone itself 3. These are effective for both scar types 5, 4.
Pressure therapy reduces scar height through local tissue hypoxia and is proven effective for hypertrophic scars 3. Compression garments are particularly useful for large surface areas 5.
Cryotherapy is most effective when combined with intralesional corticosteroids 3. This combination approach shows superior results compared to either modality alone 4.
Surgical Considerations
Simple excision alone results in 45-100% recurrence and should never be performed without adjunct therapy. 3 Excision must be combined with:
- Post-operative intralesional corticosteroids 3
- Radiation therapy using various protocols for safe and efficacious recurrence reduction 3
- Immediate post-excision adjuvant treatment 4
Emerging and Alternative Therapies
Imiquimod upregulates interferons that inhibit collagen production by fibroblasts 6, offering a newer treatment option.
Intralesional interferon (gamma and alpha-2b) successfully decreases scar height and reduces post-operative recurrences 3.
Pulsed-dye laser offers symptomatic improvement and reduces erythema associated with these scars 3, while CO2, Nd:YAG, and Argon lasers serve as destructive modalities 3.
Intralesional bleomycin and 5-fluorouracil have shown efficacy in treating abnormal scars 5, 4.
Prevention Strategy
Prevention remains the best strategy—individuals with personal or family history of keloids should be cautioned about any procedures causing skin trauma and should avoid nonessential surgery. 6, 4 This is particularly critical for keloid-prone patients, as treatment is challenging and recurrence rates are high 4.
Infection Management
Watch for secondary infections in treated scars, which can be managed with standard topical or systemic antibiotics 6.
Critical Clinical Pitfall
The most common error is treating keloids and hypertrophic scars with excision alone without adjuvant therapy, leading to near-certain recurrence 3. Always combine surgical intervention with corticosteroid injections, radiation, or other adjuvant modalities 4, 3.