CD4 and hypereosinophilic syndrome: Flow cytometry reveals the characteristic abnormal phenotype in PB with lack of surface CD3 expression (sCD3-), CD5bright, CD4 + and often loss of CD7 expression [53].The sCD3- and CD4 + phenotype detected by flow cytometry is not present in healthy individuals and should alert the pathologist to include LV-HES in the differential diagnosis.