Molecular Diagnostics of Malignant B Cell Lymphomas: Detection ofClonality and a Brief Review with our Own Results

Overview

Background.
Diagnostic approach to non-Hodgkin’s lymphomas requires a combination of laboratory methods.Methods used in morphology constitute the basis of the diagnostics; in many instances it is necessary to combinethem with methods of molecular genetics. The latter method plays a key role in the detection of B cell clonalityusing identification of the rearrangement of IGHand/or IGKgenes and in detection of the chromosomal translocationsspecific for some lymphomas.Methods and Results. Using PCR we investigated 113 patients with malignant B cell lymphomas of different types(follicular – FL, mantle cell – MCL, small cell – CLL/SLL, diffuse large cell – DLBCL). We established the IGHgene clonal rearrangement in 85 % of the cases (96/113), and the clonal rearrangement of the IGK gene in 58,3 %patients (42/72). Combination of both approaches (IGH and IGK) revealed a positive result in 90,3 % (102/113).The highest yield was rendered in patients with CLL/SLL and with MCL (100 %), and it was 86 and 87 % in caseswith FL and DLBCL.Conclusions. The detection of clonality in lymphomas helps to distinguish a malignant disease from polyclonalhyperplastic and lymphoproliferative disorders of B cells. The recognition of clonal rearrangements of the IGH andIGK genes serves for a long term monitoring of the disease activity in cases in which there are no other molecularmarkers available. The demonstration of lymphoma characteristic translocations is relatively specific and useful butat present its usefulness is reduced in cases with variable breakpoint regions.

Key words:
non-Hodgkin’s lymphomas, clonality, immunoglobulin genes, PCR.