Molecular features of GCB tumors. All analyses are restricted to GCB tumors. For refined COO, the GCB group includes tumors that were negative or indeterminant for DZsig expression. MYC and BCL2 rearrangement status were determined by FISH, and MYC rearrangement partners were identified by sequencing. (A-B) The relationship between DZsig expression and MYC rearrangement status in (A) HGBCL-NOS and (B) DLBCL-NOS. Each ribbon in the alluvial plot represents a single biopsy, linking its MYC rearrangement and DZsig expression status (left). Bar plots show the percentage of DZsig⁺ biopsies stratified by MYC rearrangement status (top right) and the frequency of MYC rearrangement stratified by DZsig expression (bottom right). (C) HGBCL-NOS biopsies were assigned into BL-like and DLBCL-like groups using a random forest classifier trained on mutational data to distinguish BL from DLBCL-NOS. The bar plot shows the percentage of tumors classified into DLBCL-like and BL-like groups stratified by DZsig expression status. Box plots display MYC and BCL2 messenger RNA (mRNA) expression levels in DZsig⁺ HGBCL-NOS tumors classified as DLBCL-like or BL-like. P values for comparisons between groups were calculated using a t test. (D) Molecular features of BL-like and DLBCL-like DZsig⁺ HGBCL-NOS tumors. Each column of the heat map corresponds to a single biopsy. MYC and BCL2 mRNA expression levels are shown as a Z-score relative to all HGBCL-NOS biopsies with available digital gene expression profiling data. IG, immunoglobulin locus; NA, not available; NEG, negative; POS, positive.