Eosinophilia and granulocytic dysplasia terminating in acute myeloid leukaemia after 24 years.

Eosinophilia of variable duration, and subsequent progression to granulocytic sarcoma and acute myeloid leukaemia, has been infrequently reported in the literature. We report a patient with eosinophilia and normal cytogenetics who, after 24 years, showed transformation to a granulocytic sarcoma of the brain. Haematological counts were normal but the marrow revealed the cytogenetic abnormality trisomy 8 in 25% of mitoses. Subsequently an AML-M2 developed, showing a complex karyotype including the trisomy 8 in all metaphases. FISH analysis combined with cytological examination identified the trisomy 8 in blasts, eosinophils and dysplastic granulocytes only. Thus progressive leukaemic transformation selectively involved the myeloid compartment.