An unusual and serious complication of topical wart treatment with monochloroacetic acid.

Numerous chemical agents are used in the topical treatment of warts. Monochloroacetic acid (MCAA) is one of these agents, which is used in low or high concentrations in most European countries. MCAA is a strong organic acid which is irritating and corrosive to the skin and has a high systemic toxicity. In addition to wart treatment, it is used for industrial purposes, such as the synthesis of certain organic chemicals. We present a case of joint deformity manifesting after the use of a preparation containing MCAA for topical wart treatment. This underlines the need to reassess the safety of MCAA use for topical wart treatment.