Intralesional methotrexate treatment for keratoacanthoma tumors: A retrospective study and review of the literature

Background: Intralesional methotrexate (MTX) is an effective treatment for keratoacanthoma (KA). Objective: We sought to systematically examine response rates and adverse events in KA treated with intralesional MTX. Methods: All cases of KA treated with intralesional MTX at our institution from 1991 to 2006 were identified. A MEDLINE and PubMed search of cases of KA treated with intralesional MTX was also performed. Results: In all, 38 cases of KA treated with intralesional MTX were identified: 18 from our institution and 20 from the literature. Intralesional MTX achieved resolution in 92%, requiring an average of 2.1 injections an average of 18 days apart. Adverse events were rare, with two reports of pancytopenia in patients with chronic renal failure. Limitations: Use of single case reports, small series, and retrospective analysis are limitations. Conclusion: Intralesional MTX is a useful nonsurgical therapy for the treatment of KA. Histologic diagnosis before initiation of treatment is preferred. A complete blood cell count at baseline and during treatment should be considered to monitor for potential cytopenia.