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

Hypereosinophilic syndromes in children are rare disorders traditionally characterized by an eosinophil count exceeding 1,500/mm³ 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, chemical-induced eosinophilia, hypoadrenalism, cancer). Until now there have only been 3 reported cases of pediatric FIP1L1-PDGFRα-positive hypereosinophilic syndromes. We describe a fourth patient, a white 14-year-old boy, the third treated with imatinib.