Acute Leukemias with Unusual Immunophenotypes / 대한임상병리학회지

ABSTRACT

BACKGROUND: Although immunophenotyping of leukemias has improved diagnostic accuracy and reproducibility, it has also caused diagnostic confusion regarding the lineage of leukemic cells. So far, lots of papers about acute leukemias with coexpression of another lineage markers with different technical methodologies and different criteria have been published in Korea and other countries. The authors investigated the frequency and immunophenotypic characteristics of the leukemias with aberrant lineage markers from data obtained at Korea University Hospital by a retrospective study. METHODS: From Jan. 1993 to Feb. 1996, 179 leukemias had been requested for immunophenotypig and 28 cases among them with unusual immunophenotypes were retrieved according to their immunophenotyping results. For the final diagnosis all the slides stained with Wright-Giemsa, peroxidase, Periodic-Acid Schiff, Sudan black B, and nonspecific esterase were re-examined, and all the flow cytometric results were reanalyzed. RESULTS: Among 28 cases, 3 cases(10%) were acute biphenotypic leukemias(BP) one with B lymphoid and myeloid markers and the other two with T lymphoid and myeloid markers. One case of intralineage bilinear acute leukemia(ILBL) with two separate populations of megakaryocytic cells and monocytic cells was noted. 6 cases(21%) were acute myeloblastic leukemias expressing lymphoid associated markers(Ly+AMLs; CD19) and 8 cases(28%) were myeloid antigen-positive acute lymphoblastic leukemias(My+ALLs, four with CD13+ and three with CD33+ and one with blastic transformation of chronic myelogeneous leukemia). Because of the change in diagnostic criteria, lymphocyte contamination, or low setting of negative control, 10 cases (36%) were not included to be of unusual immunophenotypes. CONCLUSIONS: Frequency of acute hybrid leukemia was 2.2 % of all leukemias. Ly+AMLs was 3.4%, and My+ALL was 4.4%. In conclusion, first, quality control of the flow cytometry and careful interpretation especially in terms of positive cut-off value and gating, are needed. Secondly, national guidelines for the criteria of the hybrid leukemia and My+ALLs and Ly+AMLs are necessary for the elucidation of the prognostic implication of those leukemias.