Recurrence of Anti-melanoma Differentiation-Associated Gene 5 Antibody-Positive Dermatomyositis Following Long-Term Remission: A Report of Two Cases and Review of Literature.

We report two cases of anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (DM) that recurred after long-term remission. The first case involved a 41-year-old Japanese woman, and the other involved a 31-year-old Chinese woman. Both patients were initially treated with prednisolone, tacrolimus, and low-dose intravenous cyclophosphamide. Antibody negativity was confirmed during remission. However, DM recurred in both patients after 8 and 10 years, respectively, accompanied by the reappearance of anti-MDA5 antibodies. The Japanese patient exhibited severe liver dysfunction at both onset and recurrence. In contrast, the Chinese patient presented with clinically amyopathic DM and had mild respiratory and cutaneous symptoms at both time points. The recurrence patterns were similar in both cases. A review of recurrent anti-MDA5 antibody-positive DM cases revealed common features, including female predominance, mild interstitial lung disease, low serum ferritin levels, and relatively low cumulative cyclophosphamide doses.