Nonbacterial Thrombotic Endocarditis of the Mitral Valve With Echocardiographic Appearances Mimicking a Papillary Fibroelastoma in a Middle-Aged Female Patient

Papillary fibroelastoma (PFE) and nonbacterial thrombotic endocarditis (NBTE) account for <1% of all cardioembolic strokes. When there is no evidence of infection, and an exophytic valve lesion is seen on echocardiography, PFE may be an initial imaging diagnosis. NBTE, or Libman-Sacks endocarditis, is a rare entity and can present with varied imaging findings. This report presents a case of embolic stroke and NBTE mimicking a PFE. We discuss a 49-year-old female with a past medical history of diabetes mellitus who presented with headache and right-hand numbness. The initial CT head was negative and the MRI brain showed multiple infarcts in the watershed areas where anterior and posterior brain circulation meet and overlap. A transesophageal echocardiogram (TEE) showed a left ventricle (LV) mass initially diagnosed as PFE. The patient was started on aspirin only with no anticoagulation since we thought the stroke was related to an embolus from a tumor, not a thrombus. The patient underwent surgery but the pathology report revealed a diagnosis of organizing thrombus with abundant neutrophilic infiltration and no neoplastic proliferation. This case report highlights the importance of a comprehensive evaluation of valvular masses and the diagnostic approaches currently available to help clinicians differentiate between various causes of embolic stroke like PFE, bacterial endocarditis, and NBTE. Early differentiation is critical because it can affect the treatment and outcome. This report shows that echocardiography of endocardial and valvular lesions may provide a differential diagnosis, but a definitive diagnosis requires microbiology and histopathology. Advanced imaging techniques such as cardiac CT or cardiac MRI may assist in identifying select cases that are at lower risk for subsequent embolic events, in which surgical intervention may safely be avoided.