A case of nonbacterial thrombotic endocarditis that was treatable while asymptomatic

Abstract

The patient was a 50-year-old female. She had received treatment for systemic lupus erythematosus (SLE) with glucocorticoid since she was 34 years old. Transthoracic echocardiography performed for screening showed a mass adjacent to the anterior leaflet of the mitral valve and protruding into the left ventricular outflow tract. Follow-up 3D transesophageal echocardiography depicted the mass, which occupied approximately two-thirds of the left ventricular outflow tract, and another small mass toward the left atrium. She had an opportunistic infection caused by glucocorticoid therapy; however, the blood cultures ordered several times were all negative. Infectious endocarditis was ruled out because the patient did not meet the Duke diagnostic criteria. The patient was suspected of having nonbacterial thrombotic endocarditis (NBTE) based on the formation of the masses, the diseased area, and her medical history of SLE. Head computed tomograms revealed an old cerebral infarction, suggesting that she should have a high risk of severe embolus determined by the scattered lesion pattern and thrombus mobility. The patient underwent sub-emergency mass removal and mitral valve replacement. The soft and multilocular masses and fibrin thrombus with mixed infiltrate (neutrophils and histiocytes) revealed that the patient had NBTE. The postoperative course was uneventful and no more embolic symptoms were found. She was discharged on the 19th postoperative day. NBTE frequently occurs when endothelial cells are damaged by the immune complexes and hypercoagulability due to malignant tumors. Here, we report the successful evaluation of NBTE using transesophageal echocardiography and the favorable prognosis without any neurological impairment.