Fulminant lupus myopericarditis with Class III lupus nephritis and catastrophic antiphospholipid syndrome-like thrombosis: a case report

Background Lupus myocarditis occurs in 1%–3% of systemic lupus erythematosus (SLE) cases and rarely coexists with proliferative nephritis at presentation. We describe simultaneous lupus myopericarditis, Class III nephritis, myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) positivity, and a catastrophic antiphospholipid syndrome (CAPS)-like thrombotic syndrome, highlighting the vulnerability of survivors after fulminant SLE. Case summary A previously healthy 29-year-old man presented with hypertensive pulmonary oedema, acute hypoxemic respiratory failure requiring intubation, left ventricular ejection fraction (LVEF) 36%, and dialysis-requiring acute kidney injury. Work-up showed antinuclear antibody positivity, high-titre anti-dsDNA antibodies, hypocomplementaemia, and triple-positive antiphospholipid antibodies. High-dose corticosteroids and immunosuppression were initiated, and rituximab was selected as adjunctive B-cell-depleting therapy in the setting of severe cardiac and renal SLE, with MPO-ANCA positivity raising concern for a higher-risk renal phenotype. Kidney biopsy confirmed Class III proliferative lupus nephritis, and cardiac magnetic resonance imaging (MRI) supported myopericarditis. Cerebral and splenic infarctions prompted anticoagulation, intravenous immunoglobulin (IVIG), and plasma exchange. The course was complicated by cytomegalovirus peritonitis requiring hemicolectomy. After discharge, he was readmitted with influenza A–associated septic and cardiogenic shock, LVEF 17%, recurrent multifocal cerebral infarctions, methicillin-sensitive Staphylococcus aureus bacteraemia, and invasive aspergillosis. Treatment required plasma exchange, IVIG, tracheostomy, and continuous renal replacement therapy. He survived to rehabilitation after 123 cumulative hospital days. Discussion This case illustrates convergent life-threatening autoimmune, thrombotic, and infectious complications in SLE. Cardiac MRI and kidney biopsy were essential for diagnosis. Infection-associated recurrent CAPS-like thrombosis during multi-organ failure underscores the need for infection prevention and close surveillance after fulminant lupus.