Please explain hypereosinophilic syndrome?

Too many eosinophils. Eosinophils, a type of immune cell, are too abundant in hes. High eos can be seen in allergies and in some parasitic or viral infections. If these conditions are ruled out, you are left with hes. High eos can lead to inflammation in the skin, internal organs, nerves, and the lining of blood vessels and the heart. See a hematologist or immunologist for more information.