Algorithm for the diagnosis of acute leukemia
As noted, the modern algorithm for diagnosing variants of acute leukemia includes morphological, cytochemical, immunological and cytogenetic, and sometimes molecular-biological approaches. At the same time, it should be emphasized that the morphological assessment of the composition of punctate is basic in the diagnosis of acute leukemia.
Without counting the myelogram and analysis of the morphological and cytochemical characteristics of cells of the leukemic substrate, it is impossible to interpret the data of immunological and cytogenetic studies.
The diagnostic value of each method is different for different options. Thus, by morphocytochemical methods, most variants (up to 90%) of M1 — M5 acute non-lymphoblastic leukemia can be characterized. However, M0, M7 and some cases of M6 are diagnosed only by an immunological method, as well as acute lymphoblastic leukemia.
The use of immunophenotyping for the diagnosis of acute leukemia using the ICA panel allows determining the linear orientation and / or stage of differentiation of blasts starting from the level of stem progenitors to mature forms. It is produced using flow analyzers or on bone marrow smears by the peroxidase-antiperoxidase (PAP) or phosphatase-antiphosphatase (APAP) method.
Each method has its advantages. Using a flow analyzer provides data on tens of thousands of cells in the leukemic population, the study of cells on smears makes it possible to combine immunological research with morphological and cytochemical.
The widely accepted immunological approach broadens our understanding of the biology of blast cells in acute leukemia. The emergence of new ICA allows you to allocate additional subtypes of blasts. In particular, the use of a new antimonocyte-macrophage ICA D11 (CD68) made it possible to detect myeloid differentiation in cells that were previously regarded as undifferentiated. The data obtained in the study of the mechanisms of apoptosis, played an important role in the study of the prognosis of acute lymphocytic leukemia.
There is a point of view that the variant of leukemia can be established only on the basis of immunological criteria, without using morphocytochemical data. At present, this approach has not found support, since only ICA to myeloperoxydase and lysozyme have defining specificity, and all other antigens are not so specific.
Molecular biological methods are becoming increasingly important in studying the pathogenetic mechanisms of acute leukemia. A number of observations are already used in practical medicine for the diagnosis of variants of acute leukemia. The study of the rearrangement of immunoglobulin genes and T-cell receptors plays an important role in the differential diagnosis of lymphoproliferative diseases.
The characterization of karyotype abnormalities in acute promyelocytic and myelomonoblastic leukemia with eosinophilia, taking into account the data of cytogenetic studies and the PCR reaction, makes it possible to establish a sub variant of leukemia and determine the prognosis of the disease.