Concurrent Catastrophic Antiphospholipid Syndrome, Hemophagocytic Lymphohistiocytosis, and Myocarditis Leading to Multi-organ Failure in a Patient With Systemic Lupus Erythematosus and Antiphospholipid Syndrome.

Catastrophic antiphospholipid syndrome (CAPS) is a fulminant and life-threatening manifestation of antiphospholipid syndrome (APLS), often presenting with rapid multi-organ dysfunction and high mortality despite aggressive therapy. Its associations with hemophagocytic lymphohistiocytosis (HLH) and lupus myocarditis are not well understood. We report the case of a 43-year-old woman with systemic lupus erythematosus (SLE) and secondary APLS who developed CAPS following elective mitral valve repair. Her course was complicated by renal cortical necrosis, recurrent lupus myocarditis, refractory immune thrombocytopenia, sepsis, and HLH, requiring multiple immunosuppressive modalities including corticosteroids, intravenous immunoglobulin, plasma exchange, rituximab, cyclophosphamide, and anakinra. Despite intensive multidisciplinary management across rheumatology, cardiology, nephrology, hematology, infectious diseases, and intensive care, she suffered progressive multi-organ failure and transitioned to palliative care. This case highlights the diagnostic and therapeutic complexity of overlapping autoimmune syndromes, the risks of surgical triggers in predisposed patients, and the challenges of balancing immunosuppression against infection in the setting of CAPS. It underscores the need for dynamic multidisciplinary collaboration, early recognition of HLH and lupus myocarditis overlap, and timely integration of palliative care when maximal therapy fails.