Catastrophic Antiphospholipid Syndrome in a Young Female Complicated by Systemic Lupus Erythematosus and Left Atrial Myxoma: A Rare Case Report.

Catastrophic antiphospholipid syndrome (CAPS) is a fulminant and rare variant of antiphospholipid syndrome characterized by rapidly progressive multiorgan thrombosis and a high mortality rate. Its diagnosis is often challenging due to overlapping clinical features with sepsis, thromboembolic disorders, and systemic autoimmune diseases. We report a rare and complex case of CAPS in a young woman with newly diagnosed systemic lupus erythematosus, further complicated by a left atrial myxoma, which resulted in widespread arterial thrombosis, acute ischemic stroke, pulmonary involvement, and peripheral vascular occlusion. Early clinical suspicion, prompt immunomodulatory therapy, anticoagulation, and coordinated multidisciplinary care resulted in significant clinical and radiological improvement. This case highlights the importance of early diagnosis and aggressive treatment in CAPS, particularly when unusual thrombotic triggers coexist.