Antiphospholipid antibody syndrome presenting as recurrent pulmonary thromboembolism progressing to chronic thromboembolic pulmonary hypertension: A case report

Antiphospholipid antibody syndrome (APS) is a systemic autoimmune thrombophilia with diverse clinical manifestations. Pulmonary involvement ranges from acute pulmonary thromboembolism (PTE) to chronic thromboembolic pulmonary hypertension (CTEPH). We report a 29-year-old male with no prior comorbidities who initially presented with fever, cough, and breathlessness and were treated as community-acquired pneumonia. He subsequently developed acute PTE and, over 1 year, progressed to CTEPH despite anticoagulation. Laboratory evaluation showed thrombocytopenia, reticulocytosis, positive direct Coombs test, and mild splenomegaly. Immunological testing demonstrated persistently elevated anticardiolipin Immunoglobulin (Ig)M and IgG antibodies on repeat testing after 12 weeks, fulfilling the revised Sydney criteria for APS. The patient was managed with long-term Vitamin K antagonist therapy, hydroxychloroquine, and multidisciplinary follow-up. This case highlights the diagnostic challenges of APS and emphasizes early recognition in young patients with unprovoked or recurrent thromboembolism to prevent progression to CTEPH.