Extensive nuclear lobulation in the cells of a patient with acute myelomonocytic leukemia. The role of electron microscopy for establishment of a correct diagnosis.

Extensive nuclear convolution and lobulation was found in the peripheral blood cells of a patient with acute leukemia. While the morphology of the cells, such as observed with the light microscope, was compatible with the diagnosis of acute myeloid leukemia, the finding of Sezary-like cells with the electron microscope helped to establish the diagnosis of acute myelomonocytic leukemia. This report emphasizes the importance of the electron microscope for the correct diagnosis of leukemias.