Abstract
Hypereosinophilic syndrome (HES) is a spectrum of myeloproliferative disorder, which is characterized by persistent and marked blood eosinophilia and damage to multiple organs due to eosinophilic infiltration. Idiopathic HES is identified after ruling out all other causes of eosinophilia. Poor prognosis is usually associated with cardiac involvement and malignant transformation of blood cells. We report a rare case of HES in an 8-year-old boy who presented with unilateral proptosis and torticollis. The patient responded well to corticosteroid therapy with reduction of proptosis and torticollis and normalization of serum eosinophil count.