A 28-year-old female with a history of keloid formation presents with a hypertrophic scar over the anterior chest following cardiac surgery 3 months ago. Which agent is the first-line pharmacologic intervention to prevent further scar progression and promote remodeling?

Explanation

## Pharmacologic Management of Hypertrophic Scars and Keloids **Key Point:** Intralesional corticosteroids (triamcinolone acetonide) are the first-line pharmacologic agent for hypertrophic scars and keloids because they inhibit fibroblast proliferation, reduce collagen synthesis, and promote collagen remodeling without systemic side effects. ### Mechanism of Triamcinolone Acetonide 1. **Inhibits fibroblast proliferation** — suppresses growth factor signaling (TGF-β, PDGF). 2. **Reduces collagen synthesis** — downregulates collagen I and III deposition. 3. **Promotes collagen remodeling** — shifts matrix metalloproteinase (MMP) balance toward degradation. 4. **Anti-inflammatory** — reduces inflammatory cell infiltration in the scar. ### Comparison of Scar Treatment Modalities | Agent/Modality | Mechanism | Efficacy | Indication | Limitation | |---|---|---|---|---| | **Intralesional triamcinolone** | ↓ Fibroblast proliferation; ↓ collagen synthesis | 60–80% response | Hypertrophic scars, keloids (first-line) | Requires serial injections; atrophy if overdosed | | Topical tretinoin | Enhances collagen remodeling; ↑ MMP activity | Modest | Mild hypertrophic scars; adjunct only | Slow onset; irritant; not effective for established keloids | | Sildenafil (systemic) | cGMP ↑ → ↓ TGF-β signaling | Experimental | Research phase | No proven clinical benefit; not standard of care | | Intralesional bleomycin | Fibroblast toxicity; collagen disruption | Moderate | Keloids resistant to steroids | Toxicity risk; reserved for refractory cases | **High-Yield:** Triamcinolone acetonide 40 mg/mL injected directly into the scar tissue is the gold standard. Typical regimen: 0.1–0.2 mL per cm² of scar, repeated every 4–6 weeks for 3–4 sessions. **Clinical Pearl:** The distinction between hypertrophic scars and keloids is important: - **Hypertrophic scars:** Confined to original wound boundary; respond well to intralesional steroids. - **Keloids:** Extend beyond original wound; more resistant to steroids but still first-line; may require combination therapy (steroids + cryotherapy or laser). **Warning:** Excessive intralesional steroid injection can cause fat and dermal atrophy, worsening cosmesis. Proper dosing and technique are essential. ## Pathophysiology Context Hypertrophic scars result from dysregulation of the remodeling phase: - Excessive TGF-β signaling → fibroblast proliferation and collagen overdeposition. - Imbalance of MMP/TIMP ratio → impaired collagen degradation. - Prolonged inflammatory phase → sustained growth factor production. Intralesional corticosteroids address all three mechanisms.