Background and objectives: Lineage classification needs to be established before starting chemotherapy in acute leukemias. In some cases, mixed populations can be found and these are differentiated by antigenic expression patterns.
Design and methods: We report the case of a patient with acute myelogenous leukemia whose relapse was classified as T-acute lymphoblastic leukemia (T-ALL).
Results: Flow cytometry analysis at diagnosis enabled us to identify a minor T-cell subclone which progressively increased and became dominant at relapse. There were no changes at cytogenetic and molecular levels.
Interpretation and conclusions: This case illustrates the usefulness of multiparametric flow cytometry for assessing minor leukemic populations.