Background Antiphospholipid syndrome (APS) is an acquired thrombophilia that can be associated with decreased platelet counts.
Case A 67-year-old woman presented with thrombocytopenia and a symptomatic right atrial mass suspicious of cardiac myxoma. Prolongation of the activated partial thromboplastin time (aPTT) was caused by a strong lupus anticoagulant, and bone marrow cytology was consistent with accelerated platelet clearance. The patient underwent uneventful resection of the atrial tumor, which turned out to be a calcified fibrin-rich thrombus. Definitive APS was diagnosed and long-term anticoagulation recommended.
Conclusion When evaluating patients with right atrial masses, findings of thrombocytopenia and/or aPTT prolongation should raise the suspicion of APS-associated thrombosis.