Methotrexate Sodium–Associated UV Reactivation in a Patient With Acute Lymphoblastic Leukemia

UV reactivation is an uncommon reaction characterized by recurrent inflammation in areas of prior sunburn or UV exposure following the administration of a triggering drug. We report a case of UV reactivation following administration of intravenous methotrexate sodium (MTX) 4 days after prolonged sun exposure in a 9-year-old boy with relapsed acute lymphoblastic leukemia. Our patient’s MTX-associated UV reactivation occurred despite the use of sunscreen and without prior sunburn or sun-induced erythema, which suggests that even subclinical sun damage can trigger MTX-associated UV reactivation. Therefore, patients must be strongly encouraged to utilize a 3-pronged approach to sun safety including sun avoidance, sun-protective clothing, and broad-spectrum sunscreen use, especially during the week before MTX therapy.