The correlation between C-MYC, PTEN and t(14,18)coexpessions by using floresan insitu hibridization method and high proliferating index in diffuse large B cell lymphomas

Diffuse large B cell lymphoma (DLBCL) and Burkitt lymphoma (BL) are mature aggressive B-cell lymphomas that are heterogeneous for their clinical, morphological, immunophenotypical and cytogenetic features and each of them follow a variable clinical course. The present study investigates the morphologic, immunohistochemical and cytogenetic criteria, which can differentiate between DLBCL and BL and their relation to prognosis. A total of 56 cases, 45 of which was diagnosed as DLBCL and 11 of which was diagnosed as BL in Gazi University Faculty of Medicine Department of Pathology between the years 2000 and 2007 are examined. Bcl-2, bcl-6, CD 10, MUM-1 and Ki-67 antibodies were applied immunohistochemically and t (14,18), c-myc and PTEN probes were applied by fluorescent in situ hybridization method. Results: CD 10 expression was found in 25.4%, bcl-6 in 35.6% and bcl-2 in 55.6% of DLBCL cases. It was detected that 18 out of 45 cases of DLBCL (32.1%) were of GCB and 27 (48.2%) were of ABC subtype. Although the survival rates were longer in GCB subtype when compared to ABC subtype, the difference was not statistically significant (p=0.271). There exists no significant correlation between prognosis and expressions of CD 10, bcl-6 or bcl-2 in DLBCL cases. All cases of BL (100%) expressed CD 10 and bcl-6 whereas they were all negative for bcl-2. The average Ki-67 proliferation index is BL was 97.2% (95-100%) whereas it was 63.2% (30-90%) in DLBCL. C-myc amplification was found to be positive in 80% of BL cases whereas it was positive in 31.4% of DLBCL cases and the difference was statistically significant (p=0.003). T(14;18) translocation was detected in 7.7% of DLBCL cases and in 20% of BL cases. PTEN deletion was detected in 26.7% and 9.1% of DLBCL and BL cases respectively. 77 Conclusion: The application of an immunohistochemical panel including CD 10, bcl-6, bcl-2 and Ki-67 is a quite practical and beneficial method to differentiate between DLBCL/BL. A Ki-67 proliferation index above 95% is an important indicator in the diagnosis of BL. Although c-myc amplification plays an important role the lymphomagenesis of BL, it may also be detected in some other aggressive lymphomas such as DLBCL. T(14;18) and PTEN deletion may rarely be observed in DLBCL and BL.