LAUSR

To the Editor: Eosinophilia is observed in diverse hematologic malignancies, either as a primary clonal condition or as a secondary reactive process. Hypereosinophilia (HE) is defined as absolute eosinophilia count (AEC) >1.5×109/L. HE subtypes are divided into hereditary, idiopathic, primary (clonal), and secondary (reactive). Any HE associated with organ damage was referred to as “hypereosinophilic syndrome (HES).” The term idiopathic hypereosinophilia (IHE) is most appropriate for patients with unexplained, persistent, asymptomatic HE.1 In patients with IHE, follow-up investigations should be made to rule out the development of HES or an underlying disorder. Coexistence of HE and B-cell non-Hodgkin lymphoma (BNHL) is extremely rare in children. In this study, we present a pediatric case who developed precursor B-cell lymphoblastic lymphoma of the nasopharyngeal region after the diagnosis of IHE. An 11-year-old girl presented with fatigue and cough. Lymphadenopathy and hepatosplenomegaly were absent. Laboratory tests showed leukocyte count of 146×109 and 73×109/L absolute eosinophil count (AEC). After exclusion of the secondary causes of eosinophilia, we proceeded to evaluate primary bone marrow disorders. Bone marrow aspirate revealed hypercellularity with 50% eosinophils and no excess of blasts. Karyotyping and analysis of BCR/ABL genes were normal. PDGFRA versus PDGFRB (platelet-derived growth factor receptor alpha-beta) gene analysis resulted normal. Transthoracic echocardiogram, radiograph and computed tomography (CT) of the chest, abdominal ultrasonography, and CT of the paranasal sinus were completely normal. A diagnosis of IHE was made on the basis of marked persistent and unexplained HE.