[Immunocytochemistry in the diagnosis of acute myeloid leukemia (M0)]

We examined leukemic blasts from 5 cases of AML-M0 diagnosed according to The French-American-British (FAB) classification for expression of immunological markers as well as myeloperoxidase (MPO) using flow cytometry (FCM) and immunocytochemistry (ICC). In one patient, the myeloid antigens, CD13 and CD33, were negative on FCM, but apparently positive in the cytoplasm by ICC, leading to a diagnosis of AML-M0. We examined MPO with anti-MPO monoclonal antibody in four patients by ICC, and could detect 3% or more MPO positive rates in all cases. These findings indicate that immunological studies for MPO and myeloid markers using ICC are very useful for the diagnosis of AML-M0. Two of 5 patients achieved CR, but they relapsed soon or after one year, respectively. The treatment outcomes suggest that the AML-M0 is an AML subtype with poor prognosis.