Molecular genetics and its application to the diagnosis and classification of hematopoietic neoplasms

Diagnostic pathology and hematology have been enormously helped by recent advances in laboratory techniques that enable sensitive detection and more accurate and reproducible classification of lymphoproliferative processes. This review will focus on the normal molecular mechanisms that lead to the generation of immunocompetence. In addition, some of the techniques of recombinant DNA technology that can be applied to the diagnosis and classification of hematopoietic neoplasms will be described. These common DNA techniques can be of great help in the following problems: differentiation of monoclonal (usually malignant) from polyclonal (usually benign) processes, assistance in differentiation of malignant hematopoietic neoplasms from other poorly differentiated malignant neoplasms of nonhematopoietic lineage such as melanoma or carcinoma, determination of cell lineage (i.e., T lymphocyte versus B lymphocyte), and identification of cytogenetic abnormalities such as chromosomal translocations. From these cytogenetic abnormalities probes may be constructed and used to substitute for the more labor-intensive, technically demanding conventional microscopic karyotype.