Hypertrophic Scar

Raised, red, firm scar that remains within the boundaries of the original wound, and usually improves spontaneously over 1 to 2 years. It reflects excessive collagen deposition and prolonged inflammation during wound healing.

• Common after burns (30 to 90% of deep burns), wounds that take more than 3 weeks to heal (risk rises sharply after 21 days), wounds under tension or crossing joints, infected wounds, and wounds in the sternum, shoulders, flexor surfaces and neck. It is more frequent in younger people and in darker skin.
• Risk factors: delayed healing, infection, foreign material, tension, young age, dark skin, and surgery or trauma in high tension areas. The condition often appears 4 to 8 weeks after wound closure and peaks at 3 to 6 months.
• It differs from a keloid because it does not extend beyond the wound, develops sooner, and regresses partly with time.

• Raised, firm, red to pink scar, 1 to 4 mm above the skin, with a linear or sheet like shape matching the wound. The colour fades from red to pale over 12 to 24 months.
• Itch, tenderness and pain are common in the active phase. Contractures across joints reduce range of movement, and facial contractures can distort the eyelids, lips and neck.
• Differential diagnosis: keloid, normal maturing scar (flat, pale), hypertrophic lichen planus, dermatofibroma, dermatofibrosarcoma protuberans, scar sarcoidosis, foreign body granuloma and scar carcinoma (a Marjolin ulcer in a chronic burn scar).
• Complications: contracture, functional impairment, chronic pain and itch, cosmetic and psychological distress, ulceration and, rarely, malignant change in chronic unstable scars.

• Clinical, from the timing, site and the fact that the scar stays within the wound margin.
• Measure and photograph the scar, record thickness, colour, pliability and pain, using a validated scar score. Assess joint range for contracture.
• Biopsy for a scar that ulcerates, grows, bleeds or does not behave as expected.
• Look for infection or foreign material in a persistent erythematous scar.

• Prevention and early management (the most effective stage):
  • Close wounds with minimal tension and along relaxed skin tension lines, with meticulous technique and early removal of sutures (face 5 to 7 days, trunk and limbs 10 to 14 days).
  • Treat infection and avoid delayed healing. Early excision and grafting of deep burns that will not heal within 3 weeks.
  • Silicone gel or sheeting from the time of epithelialisation, 12 to 24 hours a day for 2 to 3 months or until the scar matures.
  • Microporous paper tape applied over a closed incision, changed every 5 to 7 days for 8 to 12 weeks, to offload tension.
  • Massage with a moisturiser 2 to 3 times daily for 10 minutes, starting 2 to 3 weeks after wound closure, to soften the scar.
  • Pressure garments for burns: 24 to 30 mmHg, worn for 23 hours a day for 6 to 12 months or until the scar is mature.
  • Sun protection of the scar for 12 months with SPF 30 or more.
• Treatment of established scars:
  • Intralesional triamcinolone acetonide 10 to 20 mg/mL (up to 40 mg/mL for thick scars), every 4 to 6 weeks for 3 to 4 sessions, with a maximum of about 40 mg per session in adults. Improves height, itch and pain in about 50 to 100%. Risks are atrophy, telangiectasia and hypopigmentation.
  • Pulsed dye laser 585 to 595 nm every 4 to 8 weeks for 2 to 6 sessions to reduce redness, itch and height.
  • Fractional carbon dioxide or erbium laser, alone or with steroid delivery, for texture and contracture, 3 to 5 sessions at 4 to 8 week intervals.
  • Cryotherapy for small scars, 1 to 2 cycles every 3 to 4 weeks.
  • Intralesional 5-fluorouracil 50 mg/mL (alone or mixed 9 to 1 with triamcinolone 40 mg/mL) every 2 to 4 weeks for refractory areas. Avoid in pregnancy.
  • Botulinum toxin A to reduce tension in facial scars (evidence limited).
  • Topical onion extract and herbal gels have limited evidence.
• Itch and pain: moisturisers, cetirizine 10 mg daily, gabapentin for neuropathic pain, capsaicin cream, and lidocaine 5% patch.
• Surgical revision once the scar has matured (12 to 24 months), if it causes contracture or deformity:
  • Z-plasty or W-plasty to lengthen contractures and rotate scars into tension lines.
  • Excision with layered closure, with or without skin graft, flap or tissue expander for large areas.
  • Surgery is combined with silicone, steroid injection, or radiotherapy only for keloid like behaviour.
• Rehabilitation: early joint movement, stretching and splinting to prevent contracture after burns.
• Special groups:
  • Children: scars are more active and thicker. Use silicone, pressure and massage, with a low threshold for early review. Avoid radiotherapy.
  • Pregnancy: use silicone, tape and massage. Avoid 5-fluorouracil.
  • Dark skin: sun protection and cautious laser use, with warning of pigment change after steroids.
• Follow up: review at 3, 6 and 12 months. Refer to plastic surgery or a burns service for contractures, extensive or functionally limiting scars, and failed conservative treatment.