FIP1L1-PDGFRα-positive hypereosinophilic syndrome in childhood: a case report and review of literature.

Summary: Hypereosinophilic syndromes in children are rare disorders traditionally characterized by an eosinophil count exceeding 1,500/mm 3 on at least 2 occasions or evidence of tissue eosinophilia associated with symptoms and marked blood eosinophilia, lacking any secondary cause (such as infections, allergic disease, chemicalinduced eosinophilia, hypoadrenalism, cancer). Until now there have only been 3 reported cases of pediatric FIP1L1-PDGFRapositive hypereosinophilic syndromes. We describe a fourth patient, a white 14-year-old boy, the third treated with imatinib.