Rapid desensitization to methotrexate: a successful case in acute lymphoblastic leukemia.

Methotrexate (MTX) is a folate antimetabolite indicated for the treatment of malignant and autoimmune diseases. It is one of the most effective drugs used for the treatment and maintenance therapy of acute lymphoblastic leukemia (ALL). This paper presents a 13-year-old patient with B-type ALL who experienced a severe hypersensitivity reaction, prompting the implementation of a MTX desensitization protocol. This protocol may serve as a useful reference for future desensitization procedures. This case challenged the medical team in determining how to safely continue with the prescribed therapy. Although cases of MTX desensitization have been published in the literature, most of these are adult patients; only a few were pediatric patients; and even a fewer were patients with ALL. Given the absence of alternative treatment options, MTX desensitization was implemented, leading to a successful continuation of the therapy.