Intensive Care Management of Anti-Mi2-Positive Dermatomyositis: Lupus Overlap Syndrome

We report the case of a 49-year-old woman diagnosed with an autoimmune overlap syndrome characterized by anti-Mi2-positive dermatomyositis and systemic lupus erythematosus (SLE), presenting with extreme hyper-creatine kinase (CK) levels (>3000 U/L), progressive muscle weakness, and respiratory failure requiring intensive care management. Muscle biopsy revealed chronic inflammatory myopathy with perifascicular necrosis, and immunologic testing showed antinuclear antibody (ANA) 1:640, anti-double-stranded (ds)DNA, and anti-Mi2 positivity, confirming the diagnosis. During her clinical course, she developed hypoxemic respiratory failure, multiple endocrine dysfunctions (central hypopituitarism and autoimmune hypothyroidism), and nosocomial infections, all of which were successfully controlled. She received intravenous immunoglobulin (IVIG) therapy followed by five sessions of therapeutic plasma exchange (PLEX) (1.5 plasma volumes replaced with albumin), achieving partial muscle strength recovery, a 60% reduction in CK levels, and hemodynamic stabilization. This case represents a rare and severe form of dermatomyositis-lupus overlap syndrome with critical evolution and favorable response to combined immunomodulatory therapy. It highlights the importance of early diagnosis, multidisciplinary management, and the timely use of therapeutic PLEX as a rescue treatment for refractory autoimmune diseases in critically ill patients.