Is hyaluronidase used in the treatment of keloid scars?

Hyaluronidase in Keloid Treatment

Hyaluronidase is used as an adjunctive treatment for keloids, typically combined with corticosteroids and sometimes 5-fluorouracil, though it is not a first-line monotherapy. The evidence supports its role in enhancing drug delivery and improving outcomes when used in combination regimens, but it should not be used as standalone treatment.

Evidence-Based Treatment Approach

Primary Role: Combination Therapy

Hyaluronidase functions primarily as an adjuvant to enhance dispersion and absorption of other injected drugs 1. In keloid treatment specifically:

• Triple therapy (triamcinolone + 5-fluorouracil + hyaluronidase) showed significant improvements in lesion height, pliability, and scar scores compared to steroid monotherapy, with no complications versus telangiectasia seen with steroids alone 2

• Dual therapy (triamcinolone + hyaluronidase) protected against recurrence for 3-5 months post-surgical excision, though recurrence eventually occurred in both groups 3

• Historical protocols using 40 mg/mL triamcinolone + 150 mg hyaluronidase + 2% lidocaine achieved 84% control rates in compliant patients over 2-year follow-up 4

Mechanism and Dosing

Hyaluronidase degrades hyaluronic acid in the extracellular matrix, facilitating drug diffusion into keloid tissue 5, 6. Typical dosing ranges from 150-300 IU per injection 1, 2, administered:

• 150 IU hyaluronidase is the most commonly used dose in combination protocols 2, 4
• Injections given at 3-4 week intervals for 3 sessions initially 2
• Post-surgical prevention: inject at weeks 1,2, and 3 3

Critical Safety Considerations

Contraindications and Warnings

Do not inject hyaluronidase into or around infected or acutely inflamed areas due to risk of spreading localized infection 1. Additional precautions:

• Avoid in patients with bee venom allergy - hyaluronidase can cause allergic reactions 7
• Not for topical use or direct corneal application 1
• Should not be used to reduce swelling from bites or stings 1

Drug Incompatibilities

Hyaluronidase is incompatible with furosemide, benzodiazepines, and phenytoin 1. When used with local anesthetics, it hastens onset but shortens duration of effect and increases systemic reaction risk 1.

Clinical Algorithm for Keloid Treatment

For new/small keloids:

1. Start with intralesional corticosteroid monotherapy (triamcinolone 40 mg/mL)
2. If inadequate response after 2-3 injections, add hyaluronidase 150 IU to enhance steroid delivery

For recalcitrant/large keloids:

1. Use triple therapy: triamcinolone (0.2 cc of 40 mg/cc) + 5-fluorouracil (0.4 cc of 250 mg/5cc) + hyaluronidase (0.2 cc = 300 IU) 2, 8
2. Administer every 3-4 weeks for minimum 3 sessions
3. Assess response at 2 months post-treatment

Post-surgical prevention:

1. Inject combination therapy at postoperative weeks 1,2, and 3 3
2. Monitor closely for early recurrence (most occur 3-6 months post-treatment)
3. Retreat immediately if recurrence detected

Important Caveats

The evidence base for hyaluronidase in keloids consists primarily of small studies and case series 2, 3, 8, 4. While promising, no large-scale randomized trials establish it as standard of care 9, 10. The 2017 Pediatrics guidelines mention "emerging treatment strategies for keloid scars" but emphasize prevention remains the best strategy 11.

Hyaluronidase enhances drug delivery but does not prevent eventual recurrence - patients in combination therapy studies still experienced recurrence at 6 months 3. This underscores that keloids remain fundamentally difficult to manage regardless of treatment modality.

For patients with personal or family history of keloids, counsel them to avoid procedures that puncture the skin (piercings, tattoos, scarification), as outcomes remain uncertain even with optimal treatment 11.