Keloids are benign fibroproliferative scars with a thick, bulky, and irregular appearance.13 Though generally harmless, keloids may cause cosmetic disfigurement and induce symptoms of pain and pruritus in affected patients, drastically affecting quality of life.14
The earliest known historical records of keloidal scarring can be found in the Edwin Smith Papyrus, an ancient Egyptian medical text dating back to roughly 1700 BC.13,15 The surgical treatise described clusters of firm nodular swellings on the breast and recognized an association between these swellings and a history of trauma to the affected skin.15 In 1806, French dermatologist Jean-Louis Marc Alibert (1768-1837) referred to these raised growths as cancroïdes because of their tumor-like appearance.15 To avoid associations between these benign growths and cancer, Alibert later coined the term chéloïde or keloïde derived from the Greek word for crab claws.15 This name reflects the claw-like extensions of keloids beyond the margins of the original wound and into the surrounding skin.15
Keloids occur commonly in African and Asian populations, though limited epidemiologic data is available for specific populations.16 Estimates of the prevalence of keloids in African populations range from 6% to 16%.16 In one prospective study, keloidal scarring was more commonly observed in Black women (7.1%) and Asian women (5.2%) compared with White women (0.5%) following cesarean delivery.17
Keloids that arise within existing scar tissue represent an exuberant response to injury of the skin. Possible predisposing injuries include incisions, lacerations, abrasions, insect bites, burns, tattoos, piercings, and needle sticks.13 In a genetically susceptible individual, such injuries may result in the abnormal proliferation of fibroblasts in the connective tissue.14 Compared with normal skin fibroblasts, keloidal fibroblasts demonstrate increased expression of receptors for growth factors such as transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF).13 These growth factors are believed to contribute to the excessive production of stromal components and scar tissue.13 The pathogenesis of keloids may thus be conceived as failure to regulate the wound healing process.13
On histopathologic analysis, keloids contain type I and type III collagen bundles (called keloidal collagen) in a disarray.13 This compares with hypertrophic scars that primarily contain type III collagen organized parallel to the surface of the skin.13
Known risk factors for the development of keloids include darker pigmented skin, genetic susceptibility, and a family history of keloidal scars or folliculitis keloidalis.16
The results of a cross-sectional study discovered that Black persons with albinism were equally affected by keloids as their darker skin counterparts; both were higher than the general population.16 This suggests that genetic susceptibility may play a more important role in the pathogenesis of keloids than the degree of pigmentation in the skin.16 Keloids also tend to occur at anatomic sites with high physical tension such as the anterior chest, shoulder, deltoid, jaw, and ear lobe.14 Mechanical factors, such as intense or repetitive skin stretching at the edges of the keloid scar, may induce changes in biologic signaling pathways involved in wound healing.14
On clinical examination, keloids appear as protuberant scars originating from an existing wound but extending well beyond its borders.13 The well-circumscribed lesion may be many times larger in size than that of the original wound, and its color may appear pink, purple, or brown.13 Keloids are also frequently symptomatic, and patients may complain of pain and pruritus. These symptoms could be explained by abnormalities in small nerve fiber function caused by nerve compression by keloidal collagen.18 Other hypotheses involve the presence of mast cells within keloidal tissue that release active substances such as histamine, generating painful or pruritic sensations.18
The differential diagnosis for a keloid includes hypertrophic scar, dermatofibroma, dermatofibrosarcoma protuberans (DFSP), or cutaneous sarcoidosis. Unlike a hypertrophic scar or dermatofibroma, keloids classically extend beyond the margins of the original wound; an important distinguishing factor. If the clinical presentation becomes concerning for DFSP or cutaneous sarcoidosis, a biopsy specimen may be obtained and evaluated microscopically for uniform spindle cell fascicles or noncaseating epithelioid cell granulomas, respectively.
Although keloids represent benign growths, spontaneous regression is rare.13 Patients may pursue treatment for cosmetic purposes or symptomatic relief, though treatment of keloids may be difficult given the risk for recurrence. To attenuate the scarring process, common nonsurgical treatments include intralesional corticosteroid injections, topical silicone gel sheeting, and compression therapy.13 Invasive treatments involve surgical excision of the keloid, but these procedures may unsatisfactorily lead to a new or even larger keloid.13 To decrease the risk for recurrence, surgical procedures may be combined with adjuvant therapy such as irradiation and/or administration of corticosteroids.13 Additional therapeutic options for keloids include intralesional 5-fluorouracil injections, cryotherapy, and laser therapy.13,19
The patient outlined in this case was diagnosed with a keloid based on clinical history and examination. He is being managed with intralesional steroids to help with symptoms of pain and itching and to soften the lesion. He was counseled on avoiding future injury to the skin including elective surgical procedures, piercings, and tattoos.
Tiffany Tran, BS, is a medical student at Baylor College of Medicine in Houston, Texas; Tara L. Braun, MD, is a resident in the department of dermatology at Baylor College of Medicine.
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