Idiopathic hypereosinophilic syndrome complicated by central sinovenous thrombosis.

Idiopathic hypereosinophilic syndrome (IHES) is a rare disorder affecting cardiac, pulmonary and nervous systems with peripheral neuropathy, encephalopathy and cerebral thromboembolism. We report a 7-year-old boy with IHES who developed central sinovenous thrombosis and cerebral hemorrhage. Although he had hypereosinophilia for more than 6 months, he was asymptomatic until the sudden onset of vomiting and headache due to superior sagittal sinus thrombosis. Molecular analysis in peripheral blood did not reveal any mutation in the Fip1-like-platelet-derived growth factor receptor alpha chain (FIP1L1-PDGFRA) gene which was recently reported to be mutated in IHES. Since there must be symptoms or signs of organ involvement to fulfill the IHES criteria, we could not make a diagnosis of IHES until the onset of central nervous system involvement. We suggest that anti-coagulant therapy should be considered for asymptomatic patients with hypereosinophilia because hypereosinophilia may induce thrombosis in various organs.