Cytogenetic studies on acute myelomonocytic leukaemia (M4) with eosinophilia.

Cytological and cytogenetic studies on 17 acute myelomonocytic leukemia with bone marrow eosinophilia (M4EO) are reported. Cytological criteria include an unusual high proportion of eosinophilic cells containing abnormal granules. Abnormal karyotypes have been found in 12 patients but chromosome 16 abnormalities were present in only 9. In two of them only one such mitosis was detected whereas in 7 others inv(16)(p13q22) and/or del (16)(q22) clones were present. However in 16 cases normal karyotypes were also present. Other abnormal clones coexisted in three patients, suggesting that chromosome 16 abnormalities are not linked to a primary leukemogenic event. M4EO was found to be associated with a favourable prognosis.