Hepatitis associated with hypereosinophilia suspected to be caused by HES that also presented with the pathological features of IgG4-related disease.

A 52-year-old woman presented to our hospital due to elevated liver enzyme levels and hypereosinophilia. Liver biopsy specimens revealed chronic hepatitis with abundant eosinophils and immunoglobulin G4(IgG4)-positive plasma cell infiltration. Systemic lymphadenopathy, including that involving the hepatic hilar lymph nodes, was observed on computed tomography, and the cervical lymph node biopsy specimens exhibited lymphoid follicular hyperplasia and IgG4-positive plasma cell infiltration. It is sometimes difficult to distinguish hypereosinophilic syndrome (HES) from IgG4-related disease, as some of the clinical findings overlap. The numerous areas of eosinophilic infiltration observed in the liver indicated a diagnosis of HES in our case.