Aberrant Bcl6 protein expression in mantle cell lymphoma.
Mantle cell lymphoma is routinely considered as a Bcl6-negative B-cell lymphoma carrying the translocation t(11;14). Here we describe a series of five Bcl6-positive mantle cell lymphoma cases, including three classic and two blastoid variants. The proliferative index of these cases, measured with the Ki-67 antibody, was slightly higher than in Bcl6-negative mantle cell lymphoma cases (32.2 vs. 23.7%) Bcl6 expression was associated with translocations involving 3q27 in four of the five cases and an extra copy of the BCL6 gene in the fifth. A mutational study of the major mutational cluster in the BCL6 gene revealed no increased mutation rate, except in one case. One of the three cases displayed a high mutational index in the IgVH gene, suggesting exposure to a germinal center microenvironment. Chromosomal alterations involving 3q27 seem to be responsible for this increased Bcl6 expression, which needs to be considered when Bcl6 is used in lymphoma diagnosis.
Camacho
Francisca I
FI
Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas, C/Melchior Fernández Almagro 3, E-28029 Madrid, Spain. fcamacho@cnio.es
García
Juan F
JF
Cigudosa
Juan C
JC
Mollejo
Manuela
M
Algara
Patrocinio
P
Ruíz-Ballesteros
Elena
E
Gonzalvo
Pablo
P
Martín
Paloma
P
Pérez-Seoane
Carlos
C
Sánchez-García
Joaquín
J
Piris
Miguel A
MA
D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D002893:Chromosomes, Human, Pair 3; D004273:DNA, Neoplasm / Q000032:analysis; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D020522:Lymphoma, Mantle-Cell / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D051560:Proto-Oncogene Proteins c-bcl-6; D017422:Sequence Analysis, DNA; D014178:Translocation, Genetic
C084103:BCL6 protein, human; D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D007135:Immunoglobulin Variable Region; D051560:Proto-Oncogene Proteins c-bcl-6