Differential clinical features of patients with clinically amyopathic dermatomyositis who have circulating anti-MDA5 autoantibodies with or without myositis-associated autoantibodies.

Background: Anti-melanoma differentiation-associated gene 5 (MDA5) autoantibodies have been identified as myositis-specific autoantibodies that are often associated with clinically amyopathic dermatomyositis (CADM) and a poor prognosis due to rapidly progressive interstitial lung disease (RP-ILD) in East Asian patients. Besides anti-MDA5 autoantibodies, patients with CADM may have myositis-associated autoantibodies (MAAs), which characterize other connective tissue diseases such as rheumatoid arthritis and Sjögren's syndrome. However, the clinical significance of the coexistence of anti-MDA5 autoantibodies and MAAs in patients with CADM remains unclear.

A case of Trousseau syndrome caused by pulmonary adenocarcinoma that was controlled for one year and 10 months with thrombosis treatment using an EGFR tyrosine kinase inhibitor and chemotherapy.

A 47-year-old female with no history of previous illnesses developed cerebral infarction and was diagnosed with lung cancer, specifically EGFR mutation-positive adenocarcinoma, and Trousseau syndrome. The patient's response to anticoagulant therapy with non-fractionated heparin was very poor; however we were able to control the thrombosis with chemotherapy. She survived for one year and 10 months following treatment with gefitinib, CBDCA + PEM and erlotinib, without recurrence of thrombosis.

A case of anti-MDA5-positive rapidly progressive interstitial lung disease in a patient with clinically amyopathic dermatomyositis ameliorated by rituximab, in addition to standard immunosuppressive treatment.

Rapidly progressive interstitial lung disease (RP-ILD) in patients with clinically amyopathic dermatomyositis (CADM) associated with antibodies to melanoma differentiation-associated gene5 (MDA5) results in a high mortality rate. We experienced a case of anti-MDA5-positive RP-ILD of CADM which showed a response to rituximab, although there was no significant effect due to standard immunosuppressive treatment. This case suggests that rituximab has the potential to offer an effective agent for the treatment of anti-MDA5-positive RP-ILD of CADM.