Filamentous Left Ventricular Mass Mimicking Infective Endocarditis: A Case Report and Review of the Literature.

Cardiac masses may be detected on echocardiography, and filamentous lesions can resemble infective endocarditis, which may complicate diagnosis and management. Despite advances in imaging, distinguishing true vegetations from non-infectious lesions remains challenging.  We report the case of a 71-year-old man with multiple cardiovascular comorbidities, in whom a mobile, filamentous mass was identified in the left ventricle during routine imaging. Initial concern for infective endocarditis prompted the initiation of empirical antimicrobial therapy. However, further evaluation with transesophageal echocardiography and serial blood cultures did not confirm infection. A multidisciplinary review favored a benign etiology, with features most consistent with papillary fibroelastoma; however, histopathological confirmation was not obtained. Hence, antibiotics were discontinued, and the patient was managed conservatively with clinical and imaging follow-up and remained stable. This case highlights the overlap between IE and non-infectious cardiac lesions such as benign tumors, thrombi, and valvular excrescences. It underscores the limitations of imaging alone in differentiating these entities and emphasizes the need to integrate clinical presentation and microbiological testing along with the imaging findings. To contextualize this case, an illustrative search of previously published cases within the last 10 years was conducted, and the most relevant cases were selected. A brief review of the literature was performed, outlining reported clinical features, diagnostic strategies, and management approaches in similar presentations. Cardiac masses can mimic infective endocarditis and pose significant diagnostic challenges. Clinicians should maintain a high index of suspicion for such mimics, as a multidisciplinary, evidence-based approach is essential to avoid misdiagnosis, prevent overtreatment, and ensure appropriate patient care.