Relapsed Burkitt lymphoma with BCL2 expression
Lesson From the Friday Unknowns
The patient has a history of Burkitt lymphoma with MYC gene rearrangement (without BCL2 or BCL6 gene rearrangements), treated with R-EPOCH, most and CART infusion. He presented with lymphadenopathy.
Histologic sections show needle shaped fragments of soft tissue extensively involved by lymphoma with a diffuse pattern of infiltration.
The neoplastic infiltrate is composed of sheets of intermediate sized cells with minimal amount of cytoplasm, slightly irregular nuclear contours, vesicular chromatin and occasional small nucleoli.
Numerous admixed apoptotic bodies and tangible body macrophages are detected, imparting a starry sky appearance.
The neoplastic cells are positive for PAX5, BCL2 (diffuse), BCL6 (subset), MYC (subset), and negative for CD3, cyclin D1, TdT and EBER.
Ki-67 shows a proliferation index of nearly 100%.
Flow cytometric analysis revealed a monotypic B-cell population that is positive for CD10, CD19, CD22, CD38, and CD43 with kappa light chain restriction. The monotypic B-cells are negative for CD5, CD11c, CD23, CD30, CD200 and ROR1.
These morphologic and immunophenotypic findings are supportive of relapsed/ persistent Burkitt lymphoma.
The unusual features in this case are the diffuse BCL2 expression, and partial loss of MYC expression by IHC stains. Conversion of BCL2 expression from negative at the initial diagnosis to positive may be seen in treated/ relapsed Burkitt lymphoma cases.
Link to digital slides: https://bit.ly/3vJ2rLb | Slides labeled case 1
