Abrupt Cutaneous Lesions as First Sign of Methotrexate Toxicity

Abstract

Methotrexate is a folic acid analog and DNA synthesis inhibitor that is considered a disease-modifying antirheumatic drug and is the standard of care for rheumatoid arthritis (RA) [1,2]. Methotrexate can be associated with various side effects including stomatitis, fatigue, headaches, nausea, anorexia, and less commonly, cutaneous erosions/ulcerations, hepatotoxicity, and pancytopenia [3,4]. We report a case of a 74-year-old female taking methotrexate 2.5 mg daily for RA who presented with cutaneous erosions, stomatitis, and pancytopenia. Cutaneous erosions are a rare toxic side effect of low-dose methotrexate use typically only reported in patients with previous skin conditions such as psoriasis [5]. Cutaneous erosions in patients without a history of psoriasis are even more rare, with only nine previously reported cases to the best of our knowledge [4]. In many of these cases, cutaneous lesions have also been described as a sign of impending pancytopenia [3]. Therefore, it is important that physicians are aware of such presentations so that methotrexate can be discontinued at the first sign of cutaneous eruptions, and pancytopenia can be treated as soon as possible with rescue pharmacotherapies to prevent further complications.