Diagnostic electron microscopy. I. Hematology: differential diagnosis of acute lymphoblastic and acute myeloblastic leukemia. Use of ultrastructural peroxidase cytochemistry and routine electron microscopic technology.

We have described in detail a number of ultrastructural methods which we have found to be useful for the evaluation of hematologic cases submitted to our diagnostic electron microscopic unit. The techniques include the preparation of peripheral blood for study as both buffy coat and cell suspension specimens and the preparation of bone marrow spicules. Ultrastructural methods for the demonstration of glycogen and peroxidase are detailed. The study of such material includes light microscopic study of plastic-embedded, alkaline-Giemsa-stained one micron sections as well as ultrastructural studies. All hematological cases submitted for ultrastructural analysis in a two-year period were reviewed and are presented here. The identification of individual mature cells was relatively simple using light microscopy. Populations of blasts could also easily be recognized. Further differentiation of blasts, primarily lymphoblasts or myeloblasts, was done using ultrastructural cytochemistry where needed. These techniques can easily be done in electron microscopy units concerned with diagnostic work. We submit that pathologists and hematologists should have access to the diagnostic tools described here in order to manage patients with acute leukemia.