The Interplay of Malignancy and Endocarditis: A Report of a Rare Case of Marantic Endocarditis in Metastatic Lung Adenocarcinoma.

Endocarditis involves inflammation of the inner layer of the heart, known as the endocardium. This condition typically presents with vegetation, with bacteria and fungi usually being the primary culprits. It is divided into two main categories based on its cause: infectious endocarditis and noninfectious endocarditis (NIE). Most cases of NIE are associated with malignancies, most of which are adenocarcinomas of the pancreas and lungs. We present the case of a 63-year-old man with recently diagnosed stage 3 non-small cell lung cancer and a previous history of thrombosis to the renal and popliteal arteries alongside an extensive cardiovascular history who presented with blurry vision secondary to multiple acute ischemic strokes, initially thought to be a consequence of septic emboli due to bacterial endocarditis; however, further workup revealed otherwise, illustrating the complex relationship between malignancy and endocarditis and its ramification.