How do you approach an isolated T-cell gene arrangement found in the setting of persistent hypereosinophilia?

The lymphocyte variant hypereosinophilic syndrome (L-HES) is a rare form of reactive eosinophilic driven by clonal, phenotypically aberrant T-lymphocytes that secrete IL-5 and other eosinophilopoeitic cytokines. Diagnosis is based primarily on immunophenotyping (flow cytometry) of peripheral blood. The most common and specific T cell immunophenotype is CD3^–CD4⁺, but the CD3⁺CD4^–CD8^–TCR^αβ and CD4⁺CD7^– cells phenotypes are also well described, and other rare patterns have been reported.^{1 2} PCR for...