An unusual left ventricular outflow tract mass in a patient with systemic lupus erythematosus.

A 25-year-old female, with systemic lupus erythematosus and antiphospholipid antibody syndrome, presented with exertional dyspnoea. Echocardiography showed a large (2.0 cm × 1.1 cm), echogenic, heterogeneous mass in the left ventricular outflow tract, under the aortic valve, attached to the ventricular aspect of the anterior mitral leaflet. Tiny flagellar, frond-like structures were seen attached to the surface of the mass. There was mitral regurgitation. These echocardiographic features were suggestive of a papillary fibroelastoma, but the histopathology of the excised mass revealed it to be a thrombus, which was consistent with a diagnosis of non-bacterial thrombotic endocarditis (NBTE). This case represents a rare histopathologically confirmed NBTE presenting as an unusually large mass in the left ventricular outflow tract.