Balancing Bleeding and Thrombosis: A Rare Case of Hereditary Hemorrhagic Telangiectasia With Antiphospholipid Syndrome.

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant vascular disorder characterized by recurrent epistaxis, mucocutaneous telangiectasias, and visceral arteriovenous malformations (AVMs). Antiphospholipid syndrome (APS) is an autoimmune prothrombotic condition that necessitates long-term anticoagulation. The coexistence of these two entities presents a unique therapeutic paradox, as treatment of one often worsens the complications of the other. We report the case of a 44-year-old man with recurrent childhood-onset epistaxis, mucocutaneous telangiectasias, and a pulmonary AVM, with a positive family history fulfilling the Curaçao criteria for HHT. He presented with breathlessness, and imaging revealed necrotising pneumonia, pulmonary AVM, renal vein thrombosis, and chronic ischemic stroke. Autoimmune testing confirmed secondary APS associated with Sjögren's disease. The coexistence of active necrotizing pneumonia and AVM made the initiation of anticoagulation unsafe due to the high bleeding risk. Following clinical stabilization and successful AVM embolisation, anticoagulation with a vitamin K antagonist was cautiously initiated under close multidisciplinary supervision. One year later, the patient developed PLA2R-positive membranous nephropathy, which was managed with rituximab. This rare coexistence of HHT and APS underscores the challenge of balancing thrombotic prevention against bleeding risk. Definitive AVM management, individualized anticoagulation, and vigilant long-term multidisciplinary follow-up are essential to achieving optimal outcomes in such complex cases.