LAUSR

An intracardiac thrombus can cause serious heart failure or embolization. Most cases of right atrial thrombus occur in association with valve diseases, arrhythmia, cardiomyopathy, intravenous instrumentation, or deep vein thrombosis. The incidence is approximately 0.03%. We report a unique form of right atrial thrombus with no obvious cause. A 58-year-old woman with no previous cardiac history was incidentally diagnosed as having a mobile pedunculated mass in the right atrium (Figure 1). We suspected a myxoma and resected the mass under cardiopulmonary bypass. The mass was elastic, hard, and had a smooth capsule and stalk attached to the atrial septum beneath the fossa ovalis (Figure 2). Histologically, it was diagnosed as an organized spherical thrombus with a fibrous capsule (Figure 3).