Over expression of BCL-2 proteins occurs in

(Follicular lymphoma) (675-R) (451-Basicpathology 8th)* Follicular lymphoma - The hallmark of typical follicular lymphoma is a (14; 18) translocation that juxtaposes the IgH locus on chromosomes 14 and the BCL 2 locus on chromosome 18. This translocation is seen in upto 90% of follicular lymphomas and leads to over expression of BCL-2 protein*, BCL-2 is an antagonist of apoptotic cell death and appears to promote the survival of follicular lymphoma* Burkitt's lymphoma in 75% of cases, translocation of C-MYCproto-oncogene from its site on chromosomes 8 to a portion on chromosome 14 (214-HM).* These are tumours of mature B cells expressing surface IgM, monotypic k or X light chain, CD-19, CD-20 and CD-10 and BCL-6.* Diffuse Large B-cell Lymphoma - These mature B-cells tumours express the B-cell markers CD-19 and CD- 20 and they show variable expression of germinal center markers such as CD-10 and BCL-6. Most have surface Ig and all are negative for TdT* Chronic lymphocytic leukemia (CLL) / Small Lymphocytic Lymphoma (SLL) - The tumor cells express the pan-B cell markers CD-19 and CD-20. In addition, CD-23 and CD-5 the latter a T-cell marker that is expressed on only a small subset of normal B-cells are present on the tumor cells. There is also typically low level expression of surface immunoglobins heavy chain (usually IgG or IgM and IgD) and either k or X light chain (674-R)* Most common findings are deletions of 13q 12-14, deletions of 1 lq, trisomy 12q, and deletion of 17p.