A case of acute myelogenous leukaemia associated with eosinophilia: cytogenetic study of eosinophilic colonies showing the origin of the normal clone.

We describe a case of acute myelogenous leukaemia presenting with remarkable eosinophilia in relapse. Since the patient had chromosomal abnormalities, haemopoietic as well as eosinophilic colonies grown in culture were cytogenetically analysed to determine the origin of the eosinophils. Eosinophilic colonies as well as erythroid bursts revealed a normal karyotype, while a short-term culture of peripheral blood cells in relapse revealed an abnormal karyotype which had been observed before treatment. These data clearly demonstrate that the eosinophilia in this case originated from a normal clone. The cytogenetic analysis of eosinophilic colonies is a useful technique for the definite diagnosis of eosinophilic leukaemia or reactive eosinophilia in patients having marker chromosomes.