DLBCL90 assay: tiered classification system and scores. (A) Tiered classification of DLBCL tumors using the DLBCL90 NanoString assay. Tier 1: in the first layer of this 3-tiered classification system, PMBLsig⁺ samples are identified. Tier 2: DHITsig⁺ samples are then identified among the samples that do not have a PMBL GE signature. Tier 3: in the final tier, the remaining samples are categorized based on their COO. (B) DLBCL90 assay scores for 325 de novo DLBCL tumors from the BCC DLBCL cohort. PMBL linear prediction scores (LPSs) are plotted against COO LPSs for each sample. Low COO LPS result in an assignment to the GCB group, whereas high LPS result in an activated B-cell (ABC) assignment. High PMBL LPS results in an assignment to the PMBLsig⁺ group. Dotted lines represent the cutoffs between categories. Red, PMBLsig⁺; orange, GCB; green, unclassified; blue, ABC; black, DHITsig⁺; white, samples from patients found to have presented with bf-PMBL–like features and who were therefore excluded from further analysis.