Hypereosinophilia associated with cardiac rhabdomyosarcoma.

Hypereosinophilia, defined as an absolute eosinophil count exceeding 1,500/mm(3), is caused by a limited number of disorders. Its association with malignancy is a rare occurrence that typically denotes extensive metastasis and a poor prognosis. Several theories have been proposed to explain the hypereosinophilia associated with malignancy, focusing on the production of eosinophilopoietic cytokines by tumors. We describe a patient with hypereosinophilia associated with a cardiac rhabdomyosarcoma, review the etiologies of hypereosinophilia, and discuss the possible mechanisms.