Cytochemistry and ultrastructure in lymphoma and leukemia: utility in the diagnosis of different leukemias and the recognition of subtypes of lymphoproliferative disorders.

This review is based on the findings of multiparameter studies performed on cells obtained from over 200 cases of leukemia and illustrates the wide range of laboratory tests currently available for cell phenotype identification. Immunological techniques are not discussed and the review deals mainly with light and electron microscopic cytochemistry, transmission (TEM) and scanning electron microscopy (SEM). The importance of light microscopic cytochemistry is clearly demonstrated. In particular, paranuclear acid phosphatase, non-specific esterase (NSE) and diaminopeptidase staining are recommended as reliable T-cell markers. Ultrastructural identification of unclassified leukemic cells using techniques to detect myeloperoxidase, acid phosphatase, platelet peroxide (PPO) and NSE, is shown to be of great importance in cases of early myelo-monoblastic differentiation with negative light microscopic cytochemistry. SEM is also shown to be a reliable means of distinguishing lymphoid and non-lymphoid leukemia when some degree of differentiation is present. However SEM does not appear to contribute in the diagnosis of unclassified leukemia. The new scanning immunoelectron microscopy (SIEM) technique employing heteroantisera or monoclonal antibodies conjugated to latex microspheres (immunolatex) to detect surface receptors and specific antigens is also illustrated. This technique displays the topography of surface antigens on the cell surface of leukemic cells in 3-dimension and facilitates simultaneous visualization of the surface architecture of the labelled cells.