Classification of acute leukemia

Classification of acute leukemia

In 1976, a group of experts from France, the USA and the UK (FAB) proposed a classification of acute leukemia, based on the morphological and cytochemical features of blast cells.

Currently, you should also use the results of immunophenotyping and cytogenetic research necessary to determine the individual prognosis and the choice of adequate therapy (intensification, myelot transplantation or standard treatment, which often includes long-term maintenance chemotherapy).

In accordance with the FAB classification, on the basis of morphological examination of blood and bone marrow and cytochemical reactions, 8 types of acute myeloblastic leukemia (AML) (M0-M7) and 3 types of acute lymphoblastic leukemia (L1-L3) are distinguished. Currently, the FAB classification of ALL is not used; in AML, immunophenotyping and cytogenetic study of blast cells are almost always used additionally.

The most important for differential diagnosis is the allocation of lymphoid or myeloid lesions of acute leukemia, since there are significant differences in the treatment of patients with AML and ALL. Due to the fact that modern therapy programs for all morphological types of AML, with the exception of ALI, are usually similar, and the prognosis is usually unfavorable, the use of only the FAB classification is impractical.

It should also be borne in mind that in some patients, morphological and cytochemical studies conducted by qualified laboratory physicians either do not allow verification of the variant of RL, or give an erroneous diagnosis in some patients (in the study of peripheral blood and bone marrow preparations by various experts, the diagnosis is confirmed no more than than in 80-90% of cases).

In these cases, immunophenotyping of blast cells is indicated. Finally, at present, cytostatic therapy programs are differentiated depending on the immunological variant (first of all in ALL) and the nature of cytogenetic changes. For all these reasons, morphological and cytochemical examination of blood and bone marrow in most cases should be complemented by immunophenotyping and cytogenetic studies.

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