Non-bacterial thrombotic endocarditis masquerading as infective endocarditis: a paraneoplastic process

A 76-year-old lady presented to her local hospital with chest pain, malaise, and fever, suspected to be due to infective endocarditis. Echocardiography showed a mass on the anterior mitral valve leaflet. Multimodal imaging showed several suspected systemic septic emboli. CT showed multiple hepatic lesions and a cavitating pulmonary lesion. Magnetic resonance imaging revealed multiple cerebral lesions. Dual antibiotic treatment was commenced, though this was unsuccessful, with persistence of her symptoms. She was therefore transferred to our tertiary centre for emergency cardiac surgery. She underwent successful bioprosthetic mitral valve replacement and initially made a good post-operative recovery. However, on the fifth post-operative day, she decompensated. Transoesophageal echocardiography showed extensive thromboses on the bioprosthetic mitral valve leaflets, in the left atrium and inferior vena cava, and on the aortic valve. Subsequently, a hepatic biopsy was performed revealing metastatic adenocarcinoma. The patient unfortunately passed away shortly after, and post-mortem examination confirmed a pulmonary adenocarcinoma with hepatic and cerebral metastases. This case highlights the importance of considering paraneoplastic processes in such cases of suspected infective endocarditis with atypical features.