Diagnostic challenges in culture-negative infective endocarditis: a case of histoplasma endocarditis: a case report

Histoplasma capsulatum is a fungal infection primarily associated with respiratory diseases and conditions that compromise the immune system. Cardiac involvement is extremely rare and presents a significant diagnostic challenge, mainly owing to often inconclusive results from blood cultures, histopathology, and serological tests. This case not only highlights a rare causative organism but also examines an atypical presentation of endocarditis linked to Histoplasma capsulatum. It underscores the importance of thoroughly evaluating the patient's medical history and underlying conditions, particularly when clinical presentations and laboratory results are unusual or unclear.

A 34-year-old Hispanic male with end-stage renal disease on peritoneal dialysis owing to Immunoglobulin A nephropathy presented with atypical positional chest pain not related to physical activity. His recent medical history included pulmonary histoplasmosis. Initially, he was treated for suspected pericarditis; however, treatment was unsuccessful. Further examination and diagnostic testing revealed endocardial vegetations. The patient's presentation did not exhibit the classical clinical signs and laboratory findings typically associated with infective endocarditis. An extensive infectious workup, including serologic and microbiologic testing, failed to identify a definitive pathogen. A comprehensive review of the patient's medical history, which included recent pulmonary histoplasmosis, inconsistent compliance with antifungal therapy, and immune dysfunction related to his end-stage renal disease, was essential for guiding clinical decision-making. The patient was ultimately managed successfully with appropriate antifungal therapy and underwent surgical valve replacement.

This case highlights the complexity of diagnosing infective endocarditis when it presents atypically and is associated with rare causative organisms, such as Histoplasma capsulatum. Lacking the classical clinical features, laboratory findings, and common predisposing risk factors. It highlights the importance of a comprehensive evaluation of the patient's clinical history and overall condition to guide accurate diagnosis and effective management.