Inflammation of solar keratoses following systemic 5-fluorouracil

Several cutaneous reactions have been reported following systemic 5-fluorouracil (5-FU) for the treatment of malignancies. We report three patients with marked inflammation of the solar keratoses following continuous infusion of 5-FU for solid tumours. This side-effect with 5-FU, only previously reported in three other cases, was beneficial as most solar keratoses cleared following the inflammatory reaction. The reasons why 5-FU should be selectively taken up by solar keratoses are discussed.