An 8-year-old boy with hypereosinophilic syndrome.

Hypereosinophilic syndrome (HES) is a heterogeneous group of uncommon disorders characterized by the presence of marked peripheral blood eosinophilia and tissue eosinophilia, resulting in a wide variety of clinical manifestations. We present the case of an 8-year-old boy with HES. He complained of recurrent abdominal pain, general fatigue, and diarrhea. Laboratory data showed marked eosinophilia, elevated total IgE with positive specific IgE antibodies to common inhalant and food allergens, and elevated serum CCL17/TARC. A chest CT scan revealed central bronchiectasis, bronchial wall thickening, a mosaic attenuation pattern, and multiple small nodules in lung parenchyma; abdominal CT showed a thickened bladder wall. Gastrointestinal endoscopy revealed scarring in the gastric mucosa and mucosal erosion in the duodenum. Immunohistochemical examination demonstrated numerous eosinophil infiltrations with extensive extracellular eosinophil major basic protein deposition in the gastric mucosa. Only high-dose oral steroid was effective and cyclosporine appeared to have a steroid-sparing effect. HES is extraordinary rare in children and the long-term prognosis in pediatric HES is not well known. Comprehensive diagnostic procedures are vital for the early detection and management of complications in pediatric HES.