Clinical reviews in allergy & immunology
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Hypereosinophilic syndrome consists of a group of disorders characterized by abnormal accumulation of eosinophils in the blood or peripheral tissues, independent of known secondary causes of eosinophilia such as parasitic infection. Clinical manifestations of the condition are highly variable, ranging from asymptomatic eosinophilia to severe tissue damage and end-organ failure. This entity has been recognized for decades, with early studies identifying distinct groups of patients with differing symptoms, exam findings, laboratory abnormalities, and prognosis. ⋯ More recently, advances in the knowledge of eosinophil biology and molecular diagnostics have allowed for more specific delineation of the many disease subgroups that characterize hypereosinophilic syndrome. Identification of these groups has led to a personalized management approach to the condition, with improved diagnostic techniques as well as stratification of patients into more effective treatment groups. This review will discuss the evolution of the definition of hypereosinophilic syndrome, outline current disease classifications, provide a guide for evaluation and monitoring, and discuss current and future therapeutic modalities.
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While peripheral or tissue eosinophilia may certainly characterize drug eruptions, this feature is hardly pathognomonic for a medication-induced etiology. While delayed drug hypersensitivity reactions with prominent eosinophilic recruitment have been typically classified as type IVb reactions, their pathophysiology is now known to be more complex. Eosinophilic drug reactions have a diversity of presentations and may be benign and self-limited to severe and life-threatening. ⋯ This review also describes other localized as well as systemic manifestations of eosinophilic disease induced by various medication classes, including their individual pathophysiology, diagnosis, and management. Given the multitude of clinical patterns associated with eosinophilic drug allergy, the diagnosis can be challenging. Considerable deficits in our knowledge of these presentations remain, but the potential for severe reactions should be borne in mind in order to facilitate diagnosis and institute appropriate management.