From Pulmonary Embolism to Arterial Pseudoaneurysm: A Case of Aggressive Primary Antiphospholipid Syndrome with DOAC Failure

Abstract

Introduction: Antiphospholipid Syndrome (APS) is a major cause of acquired thrombophilia, often presenting a diagnostic challenge when clinical manifestations are multifaceted. While venous thromboembolism is common, aggressive arterial involvement represents the "hidden part of the iceberg," carrying a high risk of morbidity and therapeutic failure with newer anticoagulants.

Case Presentation: A 52-year-old male with no prior risk factors presented with acute pulmonary embolism (PE) and a butterfly malar rash. Initial investigations revealed a positive lupus anticoagulant (LA), but the 2023 ACR/EULAR score was insufficient for a formal APS diagnosis. A concurrent lumbar disc herniation caused a diagnostic bias, ascribing limb pain to neurological causes. Despite adherence to Rivaroxaban (DOAC), the patient suffered a "vascular catastrophe," characterized by a recurrent venous thrombosis and a major arterial complication: a pseudoaneurysm of the superficial femoral artery with acute popliteal occlusion. This necessitated urgent complex vascular surgery. Following persistent LA positivity at 12 weeks, the diagnosis of Primary APS was confirmed with a f inal ACR/EULAR score of 12 points (7 clinical, 5 laboratory).

Discussion: This case highlights the "APS paradox" where initial venous events may mask an underlying, aggressive arterial vasculopathy. It underscores the critical "Red Flag" of thrombotic recurrence under DOAC therapy. In high-risk APS or arterial manifestations, the TRAPS trial and EULAR guidelines confirm the mandatory superiority of Vitamin K Antagonists (VKA) over DOACs. The introduction of Hydroxychloroquine, even with negative antinuclear antibodies, provided a synergistic antithrombotic effect and protection against potential transition to Systemic Lupus Erythematosus.

Conclusion: Clinicians must look beyond the "visible part of the iceberg" in APS. Early identification of arterial fardeau, avoidance of diagnostic biases from incidental findings, and the strict prioritization of VKA over DOACs are essential to prevent life-threatening vascular escalations.

Citation

Nahidi M, Arfaoui H, El Khattabi W, Msika S, Bamha H, Bougteb N, et al. From Pulmonary Embolism to Arterial Pseudoaneurysm: A Case of Aggressive Primary Antiphospholipid Syndrome with DOAC Failure. WebLog J Pulmonol Respir Res. wjprm.2026. d0606. https://doi.org/10.5281/zenodo.19673997