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.