Introduction
Dermatomyositis(DM) is an autoimmune disease with clinical manifestations of muscle and skin damage, often accompanied by multisystem involvement, especially in the lungs(Didona et al., 2020). Positive anti-MDA5 antibodies are highly associated with interstitial lung disease (ILD), which is a major mortality factor in patients(Bai et al., 2021). Current conventional drug treatments for DM-ILD include glucocorticoids, immunosuppressants, and anti-pulmonary fibrosis drugs(Waldman et al., 2020). Long-term use of glucocorticoids can lead to many adverse reactions, a high risk of immunosuppressive infections, unpredictable adverse drug reactions, and the duration of treatment with anti-pulmonary fibrosis drugs is difficult to manage, resulting in DM-ILD patients, especially those with positive anti-MDA5 antibodies. However, the effective treatment rate is low. As a small-molecule targeted drug, many studies have confirmed the effectiveness of tofacitinib in the treatment of patients with anti-MDA5-positive DM-ILD(Chen et al., 2019, Ding et al., 2021). However, there are no reports of negative conversion of anti-MDA5 antibodies to tofacitinib treatment. Here, we report a case of anti-MDA5 antibody-positive DM-ILD in a patient who was treated with hormones and immunosuppressive agents in combination with tofacitinib and had negative anti-MDA5 antibodies, which are summarized below for clinical reference.