Mitral valve thrombus mimicking a primary tumor in the antiphospholipid syndrome

Cardiac valvular abnormalities detected by echocardiography are relatively common in patients with the primary antiphospholipid syndrome. Valvular thickening with small vegetations are typical, but reports of lesion histology are rare. We report the case of a 50-year-old man presenting with thromboembolic phenomena who had a large (>2 cm), mobile, pedunculated, mass attached to the mitral valve that had the echocardiographic appearance of a primary valve tumor. Following surgical removal, histopathologic examination demonstrated pure fibrin thrombus and serological testing confirmed the antiphospholipid syndrome. This case highlights an unusual echocardiographic appearance of intracardiac thrombus in this syndrome.