Lymphocytic variant hypereosinophilic syndromes

A large body of evidence establishing the existence of an underlying T-cell disorder in a subset of patients fulfilling hypereosinophilic syndrome (HES) diagnostic criteria has accumulated over the past decade, resulting in the definition of a novel HES variant termed "lymphocytic" HES. Although end-organ complications of hypereosinophilia are generally benign, with predominant cutaneous manifestations, long-term prognosis is overshadowed by an increased risk of developing T-cell lymphoma, as a result of malignant transformation of aberrant T cells years after HES diagnosis. Therapeutic strategies should target pathogenic T cells in addition to eosinophils, but the practical implications remain largely unexplored.