Evaluation and Differential Diagnosis of Persistent Marked Eosinophilia.

Peripheral blood eosinophilia is commonly encountered in clinical practice. The causes of peripheral blood eosinophilia are varied, ranging from benign eosinophilia to malignancy. A careful history and physical examination along with directed clinical evaluation may help determine the cause. When uncontrolled, peripheral blood eosinophilia may result in end-organ damage and life-threatening complications. This article summarizes the differential diagnosis and evaluation of persistent marked eosinophilia.