Cytochemical, immunophenotypic and ultrastructural characterization of acute leukemias: A prospective study of fifty cases

Cytochemistry and immunophenotyping are established methods in the diagnosis of most leukemias but the role of electron microscopy in diagnosis, apart from understanding the cellular morphology is less studied. We present here 50 cases of acute leukemias that were studied for morphology, conventional cytochemistry, immunophenotyping and transmission electron microscopy (TEM), including ultrastructural cytochemistry using myeloperoxidase (MPO) and platelet peroxidase activity. TEM morphology using ultrastructural cytochemistry helped in definitive typing in one mixed lineage leukemia case, one AML-M5b, one AML-M6b and one microgranular variant of APML. Thus, ultrastructural studies may be useful in accurate diagnosis of biphenotypic leukemia and further classification of acute leukemias. Also, in cases with hypercellular marrow and with associated myelofibrosis, where the marrow aspirate gives low cell count, ultrastructural studies are a valuable aid to arriving at an accurate diagnosis.