Cutaneous Erosions: An Under-Recognised and Rare Side Effect of Methotrexate Treatment, in the Absence of Systemic Methotrexate Toxicity

Sarah J Felton, Firas Al-Ni

Abstract

Methotrexate is a potentially toxic anti-folate drug widely used in the treatment of skin disease. We describe here a case of cutaneous erosions occurring in previously erythrodermic skin after only four weeks of very low-dose therapy, in the absence of features of systemic methotrexate toxicity. We thus report that localised cutaneous toxicity can occur in isolation, and propose that cutaneous erosions be considered a rare but potentially serious side effect of methotrexate, rather than a sign of actual or impending systemic toxicity.