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Bcl-2 molecular analysis in paraffin-embedded biopsies from diffuse large B-cell lymphomas.
C De Brasi1, M Narbaitz, A Rodriguez
1Departamento de Genética, Academia Nacional de Medicina, Buenos Aires. lacuteci@intramed.net.ar
Medicina
|October 29, 2000
Summary
The t(14; 18) translocation and bcl-2 gene involvement are common in diffuse large B-cell lymphoma (DLBCL). Both PCR and IHC are crucial for detecting bcl-2 gene rearrangements, especially in cases with follicular lymphoma remnants.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- The t(14; 18) translocation is frequently observed in non-Hodgkin lymphomas, particularly follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL).
- Follicular lymphoma (FL) can transform into more aggressive DLBCL, a process that may involve changes in bcl-2 expression.
- Understanding the molecular basis of DLBCL, including bcl-2 gene involvement, is critical for diagnosis and treatment.
Purpose of the Study:
- To correlate molecular detection of bcl-2/IgH rearrangement by PCR with Bcl-2 protein expression by immunohistochemistry (IHC) in DLBCL.
- To investigate the role of bcl-2 gene rearrangement and expression in DLBCL, particularly in cases with and without follicular lymphoma remnants.
- To assess the necessity of combined PCR and IHC for accurate diagnosis of bcl-2 gene involvement in DLBCL.
Main Methods:
- Analysis of 23 paraffin-embedded lymph node samples from DLBCL patients, divided into groups with (Group A) and without (Group B) FL remnants.
- Polymerase Chain Reaction (PCR) to detect bcl-2/IgH rearrangements (MBR/JH and MCR/JH).
- Immunohistochemistry (IHC) to assess Bcl-2 protein expression in lymphoma cells.
Main Results:
- PCR detected bcl-2/IgH rearrangements in 34.8% of DLBCL cases.
- Bcl-2 expression was observed in 30% of cases, correlating with PCR findings in Group B (DLBCL without FL remnants).
- In Group A (DLBCL with FL remnants), Bcl-2 IHC was positive in FL remnants but showed discordance in DLBCL areas, suggesting potential loss of expression or a secondary disease process.
Conclusions:
- The frequency of t(14; 18) in DLBCL is consistent with international reports.
- Discordant results between PCR and IHC, especially in DLBCL with FL remnants, highlight the importance of using both methods for comprehensive assessment of bcl-2 gene involvement.
- Combined molecular and immunohistochemical analysis is essential for accurate diagnosis and understanding the pathogenesis of DLBCL, particularly during histological transformation.