Mesenteric steal syndrome as an unusual manifestation of catastrophic antiphospholipid syndrome.

Catastrophic antiphospholipid syndrome is characterized by rapidly progressive multiorgan thrombosis. We report a 50-year-old man with triple-positive antiphospholipid syndrome who presented with superior vena cava syndrome, complete infrarenal aortic occlusion, and mesenteric steal syndrome. Preoperative management included plasmapheresis and systemic anticoagulation. The patient underwent open infrarenal aortic thrombectomy with aorto-aortic bypass and inferior mesenteric artery reimplantation, achieving complete clinical resolution. Histopathology revealed acute and chronic thrombosis without vasculitis. This case illustrates the coexistence of these three pathologies, an overlap not previously reported. It highlights the need for high clinical suspicion, early multidisciplinary intervention, and tailored revascularization strategies.