Left Atrial Myxoma Misdiagnosis as Infective Endocarditis: A Case Report

Introduction: Myxomas, as primary cardiac tumors, are rare neoplasms manifesting with constitutional, obstructive, and embolic symptoms. Systemic signs and symptoms make infective endocarditis one of the most common differential diagnoses. Nonspecific systemic signs and symptoms of myxomas can cause great challenges in management and treatment. Case Presentation: A 21-month-old boy was admitted to our center with a high-grade fever and gastrointestinal symptoms, but no significant respiratory complaints were noted. A history of lower limb pain and morning claudication was also present. The patient had leukocytosis with an elevated erythrocyte sedimentation rate (ESR) of two months' duration. Other acute phase reactants were detected despite previous antibiotic therapy; however, his blood culture result was negative. In echocardiography, multiple masses were seen in the left atrium near the mitral valve apparatus. The diagnosis of infective endocarditis was made, and intravenous antibiotics were prescribed for up to two weeks. He then underwent surgery because of poor response to medical treatment and renal complications. During surgery, a small mass was seen in the left atrium, and two other masses were within the mitral chordae. The histopathology report confirmed atrial myxoma. Shortly after surgical resection of the tumors, the patient's symptoms improved, and inflammatory indices returned to normal. Conclusions: Constitutional manifestations of myxoma render it reasonable to consider it as a differential diagnosis of infective endocarditis. Obtaining a complete clinical history and using imaging tools are necessary for the correct diagnosis and prevention of complications of inappropriate treatment.