[Molecular genetic features of sporadic Burkitt's lymphoma in children]

To investigate the molecular genetic features and diagnostic aspects of sporadic Burkitt's lymphoma (BL) in children.

Tissue microarray was constructed to include 64 cases of pediatric BL and 6 cases of pediatric diffuse large B-cell lymphoma (DLBCL). Immunohistochemistry and fluorescence in-situ hybridization for c-myc, bcl-2, bcl-6, IgH, myc/IgH and bcl-2/IgH gene were performed. Cases of pediatric Burkitt's lymphomas were subclassified into three groups based on their cellular orgins: the germinal center (GC) group, the late-germinal center (late-GC) group and the post-germinal center (post-GC) group.

Among 64 Burkitt's lymphomas studied, expression of CD20, CD10, bcl-6, bcl-2 and MUM1 by immunohistochemistry were 100% (64 cases), 98.4% (63 cases), 96.9% (62 cases), 0 (0 cases) and 23.4% (15 cases), respectively. Various gene rearrangements were found involving the c-myc 93.1% (54/58 cases) and IgH 82.8% (48/58 cases). Detailed rearrangements are as follows: 46 cases (85.2%) myc/IgH gene translocation along with c-myc and IgH gene rearrangement; 4 cases (7.4%) c-myc gene rearrangement without IgH and myc/IgH abnormality; 4 cases (7.4%) without c-myc, IgH or myc/IgH gene rearrangement. No case showed bcl-2 gene abnormality (100%). Fifty nine cases showed normal bcl-6 gene status. One case had bcl-6 gene rearrangement and amplification with the pathologic and immunophenotypic characteristics of BL, leading to a revised pathological diagnosis of B-cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma and Burkitt's lymphoma (DLBCL/BL). Two cases showed c-myc gene rearrangement. Two cases showed bcl-6 gene amplification and 6 DLBCL cases had a normal status of bcl-2/IgH.

A majority of pediatric sporadic BL arise from the germinal center B cells, most of which have c-myc gene rearrangement. It is useful to distinguish BL and DLBCL by multiple genes detection.