Idiopathic hypereosinophilic syndrome presenting as a single mass in the liver

Hypereosinophilic syndrome is characterized by persistent blood eosinophilia of 1,500/mm(3) or more in the absence of known causes and multiorgan dysfunction by eosinophil-related tissue damage. In Korea, some cases of hypereosinophilic syndrome with hepatic involvement have been described with prolonged benign clinical courses. Most of them were diffuse or multifocal lesions in imaging studies, and any case presenting as a large single mass lesion has not been described. Herein we report a case of hypereosinophilic syndrome with hepatic involvement in a 48-year-old woman who presented with a giant single mass. By abdominal CT scan, a lobulated well-margined heterogenous mass lesion was detected in the left lateral segment of the liver. Liver biopsy revealed severe eosinophilic infiltration and centrilobular necrosis of hepatocytes. The lesion completely disappeared after steroid administration for eleven months.