Oncogenic <b><i>MYD88</i></b> Mutations Are Rare Events in Double-Hit B-Cell Lymphomas

MYD88L265P Mutations, But No Other Variants, Identify a Subpopulation of DLBCL Patients of Activated B-cell Origin, Extranodal Involvement, and Poor Outcome

“…The only significant correlation was the expected lower frequency of BCL2 rearrangement in MYD88 L265P-mutated tumors. Only one of 39 MYD88 L265P cases showed MYC rearrangement, being in line with a recent publication showing that only one of 37 double-hit DLBCL cases had MYD88 mutation (49).…”

“…Primary central nervous system was not evaluable in the present series because those patients were excluded from the study. It is of note that we did not find especial predilection for gastrointestinal system as previously suggested by others (37,49,50). Different gene alterations in DLBCL, including MYC, BCL2, and BCL6, were analyzed.…”

“…The identification and characterization of the molecular basis of the dismal prognosis of patients with MYD88-mutant DLBCL could provide the rationale for new treatment targets in the involved pathways. Thus, MYD88 could emerge as a key biomarker in ABC DLBCL (23,25,(47)(48)(49).…”

Diagnosis of ‘double hit’ diffuse large B-cell lymphoma and B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma: when and how, FISH versus IHC

“…28,29 As defined in this discussion, there is a morphologic spectrum from many that bear some resemblance to Burkitt lymphomas (BLs) to probably a minority that more closely resemble DLBCL, NOS. 13,14,30 In some series, however, only very few of the DHL/THL are categorized as BCLU. 8 Phenotypically, they express B-cell antigens, with 64%-100% (most studies Ͼ80%) having a germinal center (GC) rather than a non-GC/activated B-cell (ABC) type phenotype/genotype as assessed mostly by IHC.…”

“…8 Phenotypically, they express B-cell antigens, with 64%-100% (most studies Ͼ80%) having a germinal center (GC) rather than a non-GC/activated B-cell (ABC) type phenotype/genotype as assessed mostly by IHC. 6,7,8,10,12,13,[15][16][17][18][19]22,23,27,[30][31][32][33][34] The BCL6 DHL are similar in many ways to the BCL2 DHL except that they are more likely to be CD10-(36% vs ϳ10%) but IRF4/MUM-1ϩ (75% vs ϳ18%), only infrequently express BCL2 (22% BCL2ϩ vs ϳ92%), and may have less cytogenetic complexity. 32 Another study with different IHC cutoff values also found less common CD10 and BCL2 and more frequent IRF4/MUM1 expression among the BCL6 DH, but did report a lower proportion of GC (vs ABC and nonclassifiable) cases and, as one might expect, a higher proportion of cases that were not associated with a FL.…”