Philadelphia-positive acute myelomonocytic leukemia with inversion of chromosome 16 and eosinobasophils.

Cytogenetic studies in a case of acute nonlymphocytic leukemia, type M4-FAB with eosinophilia, showed an acquired abnormal karyotype characterized by both a t(9;22) Philadelphia translocation and a pericentric inversion of chromosome 16, inv(16)(p13q22). This unique case shows that the previously described association between inversion of chromosome 16 and myelomonocytic leukemia with bone marrow eosinophilia is true also in Philadelphia-positive disorders. The present findings are consistent with the existence of a group of chromosome anomalies, namely t(15;17) and inv(16), which are specifically associated with one single stage of morphological differentiation of myeloid leukemic cells.