BCl-2 is classically negative in Burkitt lymphoma but weak positivity can be seen sometimes and it does not exclude diagnosis if clinical and morphological and IHC features are consistent with BL. But if intensity is moderate to strong (use background T cells, which will exhibit strong bcl-2 positivity), and MIB1 in not > 95 to 100%, its better to classify it as B cell lymphoma, unclassifiable, with features in between DLBL and Burkitt lymphoma. And what do you mean by abnormal cytogenetics? Because IHC finding of bcl-2 expression is commonly seen in double or triple hit lymphoma (as they involve bcl2), and these cases can present with features of above mentioned WHO classification category (which still a provisional entity).

Best of luck.

Hello Prashant and thanks for your input. Basically, Im interested in cases with a confirmed BL diagnosis (clinical,morphological and IHC features are consistent with BL) but show a weak bcl-2 signal (perhaps 5-15%) with abnormal cytogenetics ( in other words that these cases have a cytogenetic finding). Anyone interested in submitting cases would be welcome (perhaps start a project here on research gate). Thanks again.