A 35-year-old man presents with an acute unprovoked deep vein thrombosis of the left lower extremity. He is treated with anticoagulation and elects to discontinue treatment after 6 months. He subsequently develops polyarthralgias, fatigue, and a malar rash, and a diagnosis of systemic lupus erythematosus is made based on laboratory and clinical findings. Additional laboratory testing reveals persistent triple positive antiphospholipid antibodies, including lupus anticoagulant, high titer anticardiolipin antibodies, and anti–β2-glycoprotein I antibodies. The patient is reinitiated on anticoagulation, and the patient’s rheumatologist inquires if the addition of hydroxychloroquine could help to prevent recurrent thrombosis.