Snapshot A 50-year-old Caucasian man presents to his dermatologist for a scar that is hindering mobility in his right knee. A few weeks ago, he tripped and fell on a sharp rock, resulting in a 6 cm cut over his knee. Since then, his cut has heeled and a raised pink scar has grown over the wound. On physical exam, it is exactly 6 cm without growing beyond the original wound and is pink and shiny. His right knee does not fully extend due to the scar. To prevent further contractures, the physician discuss the possibility of surgical excision. (Hypertrophic scar) Introduction Clinical definition abnormal and excessive scarring in response to dermal injury, resulting in hypertrophic scars or keloids Epidemiology incidence keloid 6-16% of African population demographics most commonly in ages 10-30 risk factors keloid ↑ in groups with darker skin patients of African, Hispanic, or Asian descent family history wounds on chest, shoulders, upper arms, earlobes, or cheeks hypertrophic scar wounds on areas of high skin tension shoulders, neck, knees, ankles both dermal injury caused by burns wounds that take > 3 weeks to heal Etiology keloid previous trauma spontaneous hypertrophic scar previous trauma Pathogenesis dysregulation of wound healing recall normal wound healing stages inflammation, proliferation, and remodeling/maturation keloid ↑↑ type I and type III collagen disorganized and extends beyond the original wound abnormalities in melanocyte stimulating hormone may contribute hypertrophic scar ↑ type III collagen organized as parallel and confined to the original wound increased activation of myofibroblasts may contribute Prognosis keloid recurrence is frequent will not regress over time hypertrophic scar recurrence is rare may regress over time Presentation Symptoms abnormal scarring occurs after trauma or injury often itchy or painful (keloids > hypertrophic scar) keloid may take months to years to develop hypertrophic scar usually appears within 1 month Physical exam scarring along previous site of wound well-defined, firm, and shiny pink, purple, or hyperpigmented irregular borders Studies Biopsy indication only if clinical diagnosis is uncertain Histology keloid thick collagen fibers with abundant mucoid matrix disorganized type I and III collagen hypertrophic scar thin collagen fibers with minimal mucoid matrix myofibroblasts parallel type III collagen Differential Dermatofibroma protuberans Basal cell carcinoma Treatment Medical intralesional corticosteroid injections indication first-line for treatment that is often used with silicone sheeting silicone sheeting indications first-line for treatment that is often used with intralesional corticosteroid injections Non-operative laser therapy or cryotherapy indication when first-line therapies fail for larger lesions (> 0.5 cm in height) Operative surgical excision indication for scars that are associated with contractures Complications Contractures limiting mobility associated with hypertrophic scars