RT Journal Article
SR Electronic
T1 BCL-6 expression in mesenchymal tumours: an immunohistochemical and fluorescence in situ hybridisation study
JF Journal of Clinical Pathology
JO J Clin Pathol
FD BMJ Publishing Group Ltd and Association of Clinical Pathologists
SP 866
OP 869
DO 10.1136/jclinpath-2011-200185
VO 64
IS 10
A1 Walters, Matthew P
A1 McPhail, Ellen D
A1 Law, Mark E
A1 Folpe, Andrew L
YR 2011
UL http://jcp.bmj.com/content/64/10/866.abstract
AB The BCL-6 proto-oncogene encodes a transcriptional repressor protein. Among normal tissues, BCL-6 expression is confined to germinal center B-cells and a subpopulation of T-helper cells. Little is known about BCL-6 expression in mesenchymal tissues. We examined a series of solitary fibrous tumor (SFT) and other mesenchymal tumors for BCL-6 expression. Immunohistochemistry for BCL-6 was performed on 64 mesenchymal tumors [26 SFT (19 benign/uncertain, 7 malignant), 6 synovial sarcomas (SS), 5 gastrointestinal stromal tumors (GIST), 5 malignant peripheral nerve sheath tumors (MPNST), 5 leiomyosarcomas (LMS), 9 leiomyomas (LM) 4 desmoid tumors (DT), 4 perineuriomas (PN)]. Nuclear immunoreactivity was considered positive. Six BCL-6 positive SFT were also tested for BCL-6 gene rearrangement/amplification by FISH. Nuclear expression of BCL-6 was seen in 13/26 SFT, 5/5 LMS, 1/9 LM, 5/6 SS, 1/5 GIST, 1/5 MPNST, 1/4 PN, and 0/5 DT. BCL-6 expression was significantly more frequent in malignant (6/7) as compared with benign/uncertain SFT (6/19) (p=0.02) and in LMS (5/5) as compared with LM (1/9) (p=0.003). FISH for BCL-6 rearrangement/amplification was negative in all tested cases. We have observed BCL-6 expression in 50% or more of SFT, SS, and LMS, and in a lesser percentage of LM, GIST, MPNST and PN. Significantly more frequent expression of BCL-6 in malignant compared with benign/uncertain SFT and in LMS compared with LM suggests abnormalities in the BCL-6 signaling pathway may contribute to malignant transformation in at least some mesenchymal tumors. It is unlikely that BCL-6 expression in mesenchymal tumors is due to BCL-6 gene amplification or rearrangement. amplification or rearrangement.