Idiopathic hypereosinophilic syndrome with intracardiac atypical linear-shaped and floating thrombus presenting as embolic cerebral infarction

Abstract Knowledge of the multi-organ involvement in hypereosinophilic syndrome (HES) is important for the diagnosis and care of patients with this condition, even in cases with atypical presentation. This report aims to describe cerebral embolic infarction and intracardiac atypical linear-shaped thrombus in a patient with idiopathic HES and to discuss the approach of appropriate diagnosis and timely interventional management. A 55-year-old man presented with general weakness, including left-sided weakness, mild cognitive dysfunction, and mild exertional dyspnea for about 2 weeks. Initial magnetic resonance imaging for evaluating the brain showed multifocal acute to subacute infarction of both cerebral hemispheres and both cerebellums. Laboratory findings revealed leukocytosis (25,620 cells/mm3) and eosinophilia (54.9%). To evaluate the intracardiac embolic source, the patient underwent echocardiography, and a 1.5 cm linear thread-like and mobile mass was detected. Consequently, the patient was diagnosed with idiopathic HES. After bone marrow biopsy, corticosteroid and hydroxyurea were administered to control the eosinophilia. This case indicates that HES can present as a floating intracardiac atypical linear-shaped thrombus attached to the left ventricle. After appropriate diagnostic approaches, proper treatment could be given for the patient.