Immunocytochemistry of acute myeloid leukemias: an ultrastructural study by the immunogold method.

Light microscopy morphology and cytochemistry, immunology, and ultrastructural morphology, cytochemistry and immunocytochemistry studies were performed in 18 cases of acute myeloid leukemia (8 M1, 1 M2, 7 M3 and 2 M4, according to the FAB classification). The aim of the investigation was to assess the value of electron microscopy, particularly the immunogold method, in the different FAB subclasses. Transmission electron microscopy with its more recent techniques of investigation was shown to have an important role in diagnosis of early myeloid (M0-M1) and mixed (M4) cases, where it was determinant in correlating ultrastructural morphology with cytochemistry and immunology and thus identifying the different cell populations. On the contrary, in cases in which the leukemic cells showed homogeneous features, light microscopy was adequate and sufficient for correct diagnosis.