CONTRIBUTION OF IMMUNOPHENOTYPIC - AND GENOTYPIC ANALYSES TO THE DIAGNOSIS OF ACUTE-LEUKEMIA

Diagnostic accuracy in acute leukemia (AL) can be improved if traditio nal morphology and cytochemistry are supplemented with immunophenotypi c and genotypic analyses. This multiparameter approach is of crucial i mportance for the management of patients, as it enables the identifica tion of leukemic syndromes with distinct biological features and respo nse to treatment. Immunophenotyping using monoclonal antibodies has be en universally accepted as a useful adjunct to morphological criteria. This technique is particularly valuable in diagnosing and subclassify ing acute lymphoblastic leukemia and is also essential in certain type s of acute myeloid leukemia (AML), such as AML with minimal differenti ation or acute megakaryoblastic leukemia. Cytogenetic findings can be quite helpful in establishing the correct diagnosis and can add inform ation of prognostic significance. A number of specific chromosomal abn ormalities have been recognized that are very closely, and sometimes u niquely, associated with morphologically and clinically distinct subse ts of leukemia. An even more basic understanding of normal and maligna nt hematopoietic cells has begun to evolve as molecular biology begins to unravel gene misprogramming by Southern and Northern blot analysis , the polymerase chain reaction, and fluorescence in situ hybridizatio n. With the extensive use of these techniques it has become apparent t hat a proportion of leukemias exhibit the biologically relevant molecu lar defect in the absence of a karyotypic equivalent. On the other han d, apparently uniform chromosomal abnormalities such as the t(1;19) (q 23;p13), t(9;22) (q33;q11), t(8;14) (q24;q32), or t(15;17) (q21;q21) m ay differ at the molecular level. Data collected from these modern tec hnologies have introduced a greater complexity, which needs to be take n into consideration to improve both the diagnostic precision and the reproducibility of current classifications.