What is the difference between hypertrophic scar and keloid

• Both excessive fibrous tissue responses to healing

Hypertrophic scar is confined to site of original injury, is not progressive beyond 6 months and frequent in children. When a hypertrophic scar is excised it rarey recurs.

• Hypertrophic scar is a result of a problem with injury – eg burn wound, infected wound, skin sutured under tension or across Langer’s lines

Keloid extends beyond the boundary of original injury, continues to grow even years after injury, rare before puberty and will recur after excision.

• Keloid is result of genetic and racial predisposition (dark skin) in characteristic place (sternum)

What is the management of keloid or hypertrophic scaringg

• Prevention: Incision orientation, avoid tension, avoid infection

• Obseravtion – never excise within first 6 months as spontaneous regression may occur in hypertophic scarring

• Conservative – triamcinolone injection (long-acting synthetic corticosteroid), intra-lesion 5-FU, pulsed dye laser, XRT, pressure

• Surgery – Excision alone, avoiding risk factors from previous surgery and changing orientation of wound (Z plasty). Also combined with post-op conservative measures - excision combined with pre-, post- or intra-operative steroid injection, XRT after excision substantially reduces risk of recurrence.

What is keratoacanthoma

• Low grade malignancy of skin originating in pilosebaceous glands which resembles SCC.

• Once considered benign lesion that resembled malignancy, it is now recognized as an abortive malignant process.

• Grows rapidly over a few weeks and resolves rapidly over a few months leaving a residual scar.

• Central ulceration or keratin plug

What is the treatment for KA
• Surgical excision with margin of 3-5mm.

• Mohs micrographic surgery for recurrent lesions or lesions in cosmetically sensitive areas.

• XRT can be used in large tumours where excison will be difficult or disfiguring.

• Medical treatments are considered for patients where the diagnosis is clear where there are multiple tumours which are inoperable because of location or medical condition of patient.