Clonality analysis of lymphoid proliferations using the BIOMED-2 clonality assays: a single institution experience

Abstract

Background: Clonality determination in patients with lymphoproliferative disorders can improve the final diagnosis. The aim of our study was to evaluate the applicative value of standardized BIOMED-2 gene clonality assay protocols for the analysis of clonality of lymphocytes in a group of different lymphoid proliferations.

Materials and methods: With this purpose, 121 specimens from 91 patients with suspected lymphoproliferations submitted for routine diagnostics from January to December 2011 were retrospectively analyzed. According to the final diagnosis, our series comprised 32 cases of B-cell lymphomas, 38 cases of non-Hodgkin's T-cell lymphomas and 51 cases of reactive lymphoid proliferations. Clonality testing was performed using the BIOMED-2 clonality assays.

Results: The determined sensitivity of the TCR assay was 91.9%, while the sensitivity of the IGH assay was 74.2%. The determined specificity of the IGH assay was 73.3% in the group of lymphomas and 87.2% in the group of reactive lesions. The determined specificity of the TCR assay was 62.5% in the group of lymphomas and 54.3% in the group of reactive lesions.

Conclusions: In the present study, we confirmed the utility of standardized BIOMED-2 clonality assays for the detection of clonality in a routine diagnostical setting of non-Hodgkin's lymphomas. Reactions for the detection of the complete IGH rearrangements and reactions for the detection of the TCR rearrangements are a good choice for clonality testing of a wide range of lymphoid proliferations and specimen types while the reactions for the detection of incomplete IGH rearrangements have not shown any additional diagnostic value.

Keywords: BIOMED-2; IGH rearrangement; TCR rearrangement; clonality analysis; lymphomas.

FIGURE 1.

Sensitivity and specificity of the BIOMED-2 clonality assays determined in a group of T-cell lymphomas, B-cell lymphomas and reactive lesions. To determine the sensitivity and the specificity of IGH/TCR clonality assays the results of molecular testing were compared with the final diagnosis of each lymphoproliferation. The sensitivity of each clonality assay was calculated using the equation TP/(TP+FN); TP (true positives) – monoclonal (M) and “monoclonal in a polyclonal background” (M/P) results of the IGH clonality assay in a group of B-cell lymphomas, and M and M/P results of the TCR clonality assay in a group of T-cell lymphomas; FN (false negatives) – polyclonal (P) results of the IGH clonality assay in a group of B-cell lymphomas and P results of the TCR clonality assay in a group of T-cell lymphomas. The specificity of the IGH clonality assay was determined separately for T-cell lymphomas and for reactive lesions. Similarly, the specificity of the TCR clonality assay was determined separately for B-cell lymphomas and for reactive lesions. The specificity of each assay was calculated using the equation TN/(TN+FP); TN (true negatives) – P results of the IGH clonality assay in a group of T-cell lymphomas or in reactive lesions, and P results of the TCR clonality assay in a group of B-cell lymphomas or in reactive lesions; FP (false positives) – M and M/P results of the IGH clonality assay in a group of T-cell lymphomas or reactive lesions, and M and M/P results of the TCR clonality assay in a group of B-cell lymphomas or in reactive lesions.