Methotrexate and Patch Testing: A Retrospective Review

Abstract

BackgroundPatch testing while taking systemic immunosuppressants is sometimes unavoidable. Methotrexate (MTX) is the immunosuppressant currently considered least likely to negatively impact patch testing.ObjectiveThe aim of the study was to characterize a cohort of patients patch tested while taking MTX.MethodsThis is a retrospective review of patients patch tested at the University of North Carolina Dermatology in Chapel Hill, North Carolina, from 2010 to 2019, comparing patch test results of patients taking MTX with those of a control group.ResultsAn overall 52.8% positivity rate (356/674) was observed. Sixty two of 674 patients were patch tested while taking MTX, with a 46.8% positivity rate (29/62) compared with 53.4% (327/612) in the control group. The control group experienced 975 reactions, including 637 1+ reactions, 291 2+ reactions, and 47 3+ reactions. The MTX group experienced 50 reactions, including thirty-two 1+ reactions, fourteen 2+ reactions, and four 3+ reactions. The difference between the distributions was not statistically significant. Mean weekly MTX dose was 15.6 mg, whereas mean total accumulated dose was 251.6 mg. There was no statistically significant difference between weekly dose and total accumulated dose in patients with positive or negative results.ConclusionsIn our cohort, MTX had no discernible effect on patch test results, supporting use during patch testing with minimal false-negative risk.

Prevalence and trends of contact sensitization in patients with psoriasis in Lithuania

“…While some studies have shown that treatment with methotrexate is not likely to interfere with patch testing results, due to the fact that its effect is dose-dependent, it could have still made an influence on our results. 28 , 29 Furthermore, while other potential causes of psoriasiform lesions in the differential diagnosis could not be ruled out, it is crucial to note that patients included in this study exhibited a typical presentation of psoriatic lesions. Also, a larger cohort would enhance the accuracy of statistical analysis.…”