Refractory Antiphospholipid Syndrome With Thoracic Outlet and Superior Vena Cava Syndromes: A Complex Case of Recurrent Thrombosis

Thoracic outlet syndrome (TOS) and superior vena cava syndrome (SVCS) are rare and debilitating conditions that can cause vascular compression, hypercoagulable states, and central venous obstruction. This is the case of a 39-year-old female with treatment-resistant antiphospholipid syndrome (APS), hereditary angioedema (HAE), and mast cell activation syndrome (MCAS) complicated by SVCS and venous TOS. Her clinical course was further challenged by recurrent venous thromboembolism with treatment failure on multiple direct oral anticoagulants (DOACs), with warfarin being the only effective medication. Furthermore, the patient experienced several thrombotic events, which included: left subclavian vein thrombosis, recurrent deep vein thromboses (DVTs), and septic thrombophlebitis (methicillin-sensitive <i>Staphylococcus epidermidis</i> bacteremia) involving the left internal jugular vein. Her vascular history also included left lower lobectomy for pulmonary nodules and right cerebral stenting for reversible cerebral vasoconstriction syndrome (RCVS). The patient also had gastroparesis attributed to HAE-related visceral edema. This case illustrates the challenges posed by overlapping rare disorders, where the combination of APS and mechanical venous obstruction resulted in recurrent thromboses, complicated further by the patient's complex past medical history. Our findings highlight the limitations of conventional anticoagulation strategies in treatment-resistant APS and emphasize the need for multidisciplinary approaches.