Acute lymphoblastic leukemia
Apr 25, 2018
The classification of ALL( table) developed by the FAB is based on the division of lymphoblastic leukemia into morphological features of the blasts into three types: microlymphoblasts( L1), less differentiated cells( L2), large cells resembling immunoblasts identical to tumor cells in Burkett's lymphoma( L3).
In red bone marrow, with ALL, a marked lymphatic infiltration is observed, with reduced erythro- and thrombocytopoiesis. The bulk of cells of peripheral blood and bone marrow is characterized by small dimensions( 9-14 nm) and rounded shape. Blas-you of a larger size have a large, centrally located nucleus with a delicate chromatin structure that occupies almost the entire volume of the cell. One nucleol is determined in the nucleus. The cytoplasm has a different form of basophilia.
Table Morphological criteria of FAB classification of ALL
There is no great practical value in dividing ALL into types according to the FAB classification. To determine the prognosis and you
borax optimal tactics for treatment of ALL is much more important is the phenotypic classification of ALL.The basis for the phenotypic classification of ALL is the concept of the stages of differentiation of normal T and B lymphocytes. In Table.the classification of ALL, developed by the European Group on the Immunological Characterization of Leukemia( EGIL), is given.
ALL T-lines: CD3 + cytoplasmic or membrane( most cases of TdT +, HLA DR-, CD34-, but these markers do not play a role in diagnosis and classification)
ALL T-line: CD3 + cytoplasmic or membrane( most cases of TdT +HLA DR-, CD34-, but these markers do not play a role in diagnosis and classification.)
Table Immunologic characteristics ALL
ALL B line: CD19 + and / or CD79a + and / or CD22 + cytoplasmic( expression of at least two pan-B-cellMarkers, most cases of TdT +, HLA DR +, mature B-ALL often TdT-)
In accordanceuu with phenotypic classification embodiment is divided into four T-ALL.All T-ALL are characterized by expression in the cytoplasm or on the CD3 T-lymphocyte membrane. Pro-T-ALL( T1) variant has in addition to cytoplasmic CD3 only one membrane pan-T-marker - CD7.Pre-T-ALL( T2) is characterized by the additional expression of one or two pan-T markers - CD2 and CD5 in the absence of CD1 and CD3
on the membrane. For B-lymphocytes, at all stages of differentiation, the expression of Ar CD19, CD22 and CD79a, whichconfirm the belonging of leukaemic blasts to the B-line. ALL from B-lymphocytes( precursors) is also characterized by the constant and high expression of Ar second-class histocompatibility( HLA DR) and terminal deoxynucleotide-transferase( TdT).The isolation of four phenotypic variants of B-ALL is based on the expression of certain markers cited in the classification( common-in-ALL - CD10, pre-B-ALL - cytoplasmic IgM, etc.).