Cytochemistry and immunocytochemistry in bone marrow examination: contemporary techniques for the diagnosis of acute leukemia and myelodysplastic syndromes. A combined approach.

Although the cytologic type of acute leukemia can often be suspected on the basis of conventional panoptically stained specimens, it is important to document as precisely as possible the type of leukemia before the institution of specific treatment. At the present time, this documentation can usually be achieved with cytochemical stains that demonstrate enzymes and/or metabolites of diagnostic value. Additional immunocytochemical stains can often identify cells of ambiguous origin on the basis of cell-specific properties such as antigens. Immunophenotyping has proven to be of considerable value in the diagnosis and classification of ALL. At present, the practicality of surface antigen phenotyping in ANLL remains to be documented. The identification of hybrid leukemia is clearly facilitated with immunologic markers. Present criteria for the diagnosis of myelodysplastic syndrome do not include immunophenotyping. By use of a combination of morphologic criteria, traditional cytochemical stains, and immunocytochemical techniques, it is possible to establish the cell of origin in the large majority of cases of acute leukemia. Those rare cases in which the usual patterns of reactivity do not occur provide additional stimuli to develop new cytochemical and immunologic methods that will help to establish the origin of the leukemic blast.