Hypereosinophilia syndrome or eosinophilic leukaemia. A case report of a one-year-old infant.

The case history of a one-year-old girl, who suffered from a fatal hypereosinophilia syndrome (HES), is presented. It is demonstrated that in this particular patient the origin of the HES has been a variant type of juvenile chronic myeloid leukemia. Clinical and pathologic data are presented. This is the youngest patient ever described as having suffered from fatal HES caused by a leukemic process.