Evaluating serum level of thymidylate synthase in post burn keloid patients before and after intralesional injection of 5-fluorouracil.

Background: Keloids are fibrous lesions formed at the site of trauma due to types I and III collagen irregular production. The presence of thymidylate synthase (TS) is a must for DNA synthesis and repairs causing cell death. 5-fluorouracil (5-FU) is a fluorinated pyrimidine analogue acting as an anti-metabolic agent that inhibits thymidylate synthase and interferes with ribo-nucleic acid (RNA) synthesis.