Figure 1.

Morphological features, cell-of-origin (COO) subtypes and clonality analysis of diffuse large B-cell lymphoma-like and Burkitt lymphoma-like areas. (A) Sample A1 shows diffuse large B-cell lymphoma-like (DLBCL-like) histology (diffuse growth of large-sized polymorphous cells with prominent nucleoli); sample A5 displays Burkitt lymphoma (BL-like) features (‘starry sky’ pattern, medium-sized tumor cells with finely clumped chromatin, multiple nucleoli and basophilic cytoplasm, admixed with numerous tingible body macrophages) (Giemsa stain; original magnification 20* and 200*). (B) DLBCL-like area exhibits a ‘non-germinal center’ (non-GC) profile according to Hans algorithm and an activated B-cell (ABC) signature by gene expression profiling (left panel); conversely, BL-like area presents a ‘germinal center-like’ phenotype and a germinal centre-like (GCB) signature (right panel). Both samples display the same immunoglobulin (IGH) gene rearrangement (C) and identical hypermutated IGHV4-34 sequences (D). No detectable amplifications were observed using the leader primers; therefore, the sequences were obtained with FR1 consensus primers: nucleotide changes are shown from codon 15 in FR1-IMGT to the end of CDR3-IMGT. Hyphens (-) indicate nucleotide identity with the germline, dots (.) represent gaps. (E) IMGT/V-QUEST summary displaying V-D-J alignment, nucleotide identity to germline (%), and CDR3 sequence.