Acute eosinophilic leukemia: characterization by cytochemistry, chromosomal analysis, and in vitro colony formation.

A pericentric inversion of chromosome 16 and acute myelomonocytic leukemia [AMMoL, M4 French-American-British (FAB)] with abnormal bone marrow eosinophils has recently been shown to form a new cytogenetic-clinicopathological entity. A patient otherwise undistinguishable from the more typical cases but lacking the FAB criteria for AMMoL is described. In such a situation, in vitro colony formation closely resembling that of acute myoblastic leukemia together with the clinical, morphological, cytochemical, and cytogenetic characteristics reported might serve as an indicator that these patients run an acute course justifying a diagnosis of acute eosinophilic leukemia and immediate institution of aggressive chemotherapy. The importance of the in vitro growth pattern regarding the differential diagnosis of disorders associated with predominant proliferation of eosinophils is discussed.