The use of diphenylcyclopropenone in the treatment of recalcitrant warts

Background: The treatment of recalcitrant palmoplantar and periungual warts using topical immunotherapy with diphenylcyclopropenone (DPC) was reviewed retrospectively over a seven-year period. Methods: Two hundred eleven patients were sensitized during this time. The patients consisted of 90 males and 121 females and were between 5 and 78 years old. Twenty-three patients were lost to followup. Of the remaining, 4 were undergoing treatment at the time of evaluation, 1 patient failed sensitization, and 1 patient became pregnant. Four discontinued because of side effects, 3 because of financial reasons, and 18 patients discontinued treatment prior to completing the minimum required applications (defined as 6), producing a dropout rate of 12% (25/211). Three patients had additional treatment during the course of DPC and were not included in the study. The remaining 154 patients were classified as nonresponders or responders. Results: The responders consisted of 135 individuals (87.7%) that had complete clearance of warts. Reported adverse effects were local and included with pruritus (15.6%), with blistering (7.1%), and with eczematous reactions (14.2%). The majority of the patients tolerated the treatment very well. One patient developed local impetigo. Patients had an average of 5 treatments over a 6-month period. Conclusions: Topical immunotherapy using DPC is an effective treatment option for recalcitrant warts. It should be considered as first-line treatment for warts based on its high response rate, absence of scarring, and painless application.