Routine immunophenotyping in acute leukemia: Role in lineage assignment and reassignment

Diagnostic evaluation of acute leukemia at Roswell Park Cancer Institute has routinely included immunophenotyping by multiparameter flow cytometry. In a retrospective analysis of 646 cases, morphology and cytochemistry established lineage in 612, but not in 34 (5%), of which 26, 5, and 3 were myeloid, undifferentiated, and lymphoid, respectively, based on immunophenotyping. In addition, immunophenotyping changed the lineage assigned based on morphology and cytochemistry in 11 cases (2%); 8 changed from lymphoid to myeloid, and 3 from myeloid to lymphoid. The data support routine inclusion of at least limited immunophenotyping in the diagnostic evaluation of acute leukemia.