Eosinophilia is usually defined as an eosinophil count of more than 500/microL in peripheral blood.1 An eosinophil count of more than 1,500 is referred to as hypereosinophilia (HE); hypereosinophilic syndrome (HES) is defined as HE associated with organ dysfunction attributable to eosinophilia.2
Explore this issueMay 2018
Eosinophilia can occur due to infectious, malignancy, autoimmune or allergic etiologies. However, a significant number of patients do not have any identifiable etiology and are classified as idiopathic hypereosinophilic disorder, or hypereosinophilic disorder of unknown significance when there’s no end organ involvement.
Numerous stem cell mutations have been proposed to be associated with primary/idiopathic HE conditions.3,4 Heterogeneity of eosinophilic disorders can often make diagnosis challenging.
Below, we present a case of hypereosinophilic disorder that underscores the importance of detailed history and physical examination in the evaluation of hypereosinophilia.