Keloid vasculature reacts to intralesional injection therapies but does not predict the response to treatment: Biopsies from double-blinded, randomized, controlled trial

Keloids are benign fibroproliferative skin scars that expand beyond the original wound site. Hypoxia and angiogenesis are thought to drive pathological scar formation in keloids. We utilized biopsies collected before, during and after the double-blinded randomized controlled trial (RCT) comparing the intralesional treatments of 5-fluorouracil and triamcinolone injections in 48 human keloids. We could not detect any cells expressing the hypoxia markers (carbonic anhydrase 9 and hypoxia-inducible factor 1α) in the three distinct regions of keloid dermis. The amount of epidermal hypoxia could not predict the response to treatment. The middle dermis of the patients obtaining a clinical response to the intralesional injections showed significant increase in mature blood vessels and in lymphatics after the treatment. Our study does not support hypoxia being the driver behind keloid formation but demonstrates that the patients obtaining a response to intralesional therapies develop more blood vessels and lymphatics in the middle dermis of the keloids during the treatment.