Idiopathic hypereosinophilic syndrome: a rare but fatal condition presenting with common symptoms

INTRODUCTION: Idiopathic hypereosinophilic syndrome (IHES) is a leukoproliferative disorder characterized by cytokine-induced overproduction of eosinophils with resultant multiorgan infiltration and damage. The diagnostic criteria includes evidence of end organ damage, exclusion of all other causes of eosinophilia and sustained absolute eosinophil count (AEC) > 1,500 cells/mcl for at least 6 months. CASE: An 88-year-old Caucasian female presented with persistent severe chronic cough, weight loss and rhinorrhea unresponsive to various treatments. Her workup during admission revealed absolute eosinophil count of 17,447 and bone marrow biopsy showed eosinophilia with no lymphoproliferative process. After excluding all other causes of eosinophilia, a diagnosis of IHES was made and prednisone was started. Symptoms resolved and her absolute eosinophil count progressively decreased. CONCLUSION: IHES mimics several other diseases. Mild eosinophilia should be worked up irrespective of age and sex. A high index of suspicion is required for earlier diagnosis and treatment, which could reduce morbidity and mortality.