Idiopathic Hypereosinophilic Syndrome in a Child.

The idiopathic hypereosinophilic syndrome (HSE) is a new heterogeneus disorder characterized by persistent unxplained hypereosinophilia (eosinophil count > 1.5 x 10 ⁹ /L) persisting at least 6 months with possibile organ involvment. The diagnosis of HSE is based on exclusion criteria of other causes of eosinophilia. We reporte a case of an atopic 3 year-old male child with a history of eczema since first years of life and hypereosinophilia. At admission he showed severe generalized eczema with pruritus pain in the jonts, fever, several athsma, mild hepatosplenomegaly and lymphoadenomegaly. Biological findings included mild hypochromic microcytic anemia (Hb 10.5 g/dl, MCV 65 μ³, MCH 23 pg) due to heterozygous α thalassemia -delection (α) ⁻³⁷-, hyperleukocitosis (WBC 45.5 x 10 ³ / μL) and hypereosynophilia (20.9 x 10 ³ / μL). Bone marrow aspiration revealed absence of blast cells, mild reduction of myeloid (40%) and erythroid cells (10%) with increased M/E ratio 6/1. The eosynophilic cells represented 35%. Some of these cells presented cytoplasmatic atypia. Blood lymphocyte immunophenotypical analysis showed increased values of T lymphocytes CD₃₊, B lymphocytes CD₁₉₊ and T helper lymphocytes CD₃₊CD₄₊ Serum IgE levels were increased. Cytokines serum levels were undectable. Karyotype was 46XY. Non cytogenetic abnormalities were found in myeloid cells. Specific viral antibodies as well as autoantibodies and parasitologic assessements were negative. Corticosteroids were used with mild clinical improvement, followed by worsenings when the drug was stopped. The absence of blast cells or cytogenetic abnormality favor the diagnosis of HSE. However some patients in whom a diagnosis of idiopathic HSE appears appropiate may subsequently develope malignancies. A systematic survey of a large group of patients with otherwise unexplained eosinophilia is needed as well as a prolonged follow up of patients to early evaluate in each case neoplastic risk.