Bcl-6 is a nuclear transcription marker that is normally expressed on follicular (germinal center) B-cells and a subset of intrafollicular T-cells. It is usually expressed in cases of follicular lymphoma, and a subset of diffuse large B-cell lymphomas (40%).
Follicular Lymphoma
In follicular lymphoma, the expression intensity of bcd-6 is an independent prognostic marker. In general, the stronger the bcd-6 expression, the better the overall and disease free survival. Overall, at least 88% of cases show expression.
DLBCL
In cases of diffuse large B-cell lymphoma, bcd-6 is used as part of a panel, including CD10 and MUM-1, to sub classify cases as either germinal center or non-germinal center immunophenotypes (Hans’ classifier). Germinal center immunophenotypes are associated with better survival compared to a non-germinal immunophenotype.
Reporting
Bcl-6 is generally interpreted and reported in a semi-quantitative manner with regard to intensity (e.g. 1+, 2+, or 3+) and distribution (e.g. >50% of the lymphoma cells)
Bcl-6 Expression Pattern
- B-cells (centrocytes & centroblasts)
- T-cell (subset of CD4+)
- T-ALL
- Thymus
- Follicular Lymphoma
- Diffuse Large B-Cell Lymphoma
- Burkitt Lymphoma
- Nodular Lymphocyte Predominate Hodgkin Lymphoma
- Classical Hodgkin Lymphoma (negative or low expression)
- Monocytic & Myeloid Cells (dim)
- T-Cell Lymphomas (AILT, etc.)
Photomicrographs
References
Boyd SD, Natkunam Y, Allen JR, Warnke RA.Selective immunophenotyping for diagnosis of B-cell neoplasms: immunohistochemistry and flow cytometry strategies and results. Appl Immunohistochem Mol Morphol. 2013;21: 116–131. doi:10.1097/PAI.0b013e31825d550a
Bilalovic N, Blystad AK, Golouh R, Nesland JM, Selak I, Trinh D, et al. Expression of bcl-6 and CD10 Protein Is Associated With Longer Overall Survival and Time to Treatment Failure in Follicular Lymphoma. Am J Clin Pathol. 2004;121: 34–42. doi:10.1309/TNKL7GDC66R9WPV5
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Bone Marrow IHC. Torlakovic, EE, et. al. American Society for Clinical Pathology Pathology Press © 2009. pp. 226.
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Khokhar FA, Payne WD, Talwalkar SS, Jorgensen JL, Bueso-Ramos CE, Medeiros LJ, et al. Angioimmunoblastic T-cell lymphoma in bone marrow: a morphologic and immunophenotypic study. Hum Pathol. 2010;41: 79–87. doi:10.1016/j.humpath.2009.06.016
Hans CP, Weisenburger DD, Greiner TC, Gascoyne RD, Delabie J, Ott G, et al. Confirmation of the molecular classification of diffuse large B-cell lymphoma by immunohistochemistry using a tissue microarray. Blood. 2004;103: 275–282. doi:10.1182/blood-2003-05-1545