Hypereosinophilic syndrome.

BACKGROUND: Hypereosinophilic syndrome (HES) is a myeloproliferative disorder characterized by persistent eosinophilia associated with multiple organ damage.

OBJECTIVE: To increase awareness of the rare but potentially life-threatening disease and to provide a brief overview of the clinical presentation, diagnosis, and management of HES.

METHODS: Pertinent data from the patient's clinical course was incorporated with salient articles on the topic.

RESULTS: A case of HES is presented, followed by discussion of the clinical characteristics, diagnosis, and management. Clinical pearls and pitfalls are emphasized for the practicing allergist, clinical immunologist, and fellow-in-training.

CONCLUSION: A diagnosis of HES should be considered in patients with an absolute eosinophil count of >1500 cells/μL documented on two occasions at least 1 month apart, and/or in those with pathologic confirmation of tissue hypereosinophilia. The decision to treat HES should be guided by both the clinical presentation and results of laboratory and mutational analysis.