Keloids are nodular, often lobulated, firm to hard but movable, non-encapsulated masses of hyperplastic scar tissue. It is a result of an overgrowth of granulation tissue (collagen type 3, early) at the site of a healed skin injury which is then slowly replaced by collagen type 1 (late). The pathogenesis is complex and involves both genetic and environmental factors and the exact mechanism is still unknown. Growth factors like VEGF, TGF-β1, TGF, β2, CTGF and PDGF-α play are overexpressed, but it remains unclear if this is the cause or the consequence of the excessive scarring. Keloids can closely resemble lobomycosis but can also be confused with lepromata and less likely with lesions of diffuse cutaneous leishmaniasis. Africans are particularly susceptible to keloids. The tribal scar pattern following scarification is based on this property. Keloids occur in all types of conditions, for example after burns, cauterisation, vaccinations, on in-growing beard hair, folliculitis or even spontaneously. Keloids are raised and sharply delineated. The overlying skin is reddish and shiny. The lesion can be itchy or painless and the dimensions can be unexpectedly large. Keloids can develop later, up to years after the initial trauma. Treatment is difficult. Treatment options include resection, cryotherapy, intralaesional corticosteroids, 5-fluorouracil or bleomycin. Complete excision is followed by recurrence in 70% of cases. Excision within the edges of the lesion is recommended but the result is aesthetically unsatisfactory. Corticosteroids have no effect on the fixed lesions, but can prevent their recurrence by injections localised around the site of the original lesion if started 3 weeks after surgery and repeated weekly for the following 8-12 weeks. Bigger and horizontally growing keloids are more likely to recur after treatment.
