MYD88L265P mutation is a highly specific marker for the nonGCB/ABC DLBCL molecular subtype

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Mutations in MYD88, an innate immune adapter, are selectively found in certain B-cell lymphomas.
• Understanding the prevalence and associations of MYD88 mutations can refine lymphoma classification.

Purpose of the Study:

• To investigate the frequency and clinicopathological correlations of the MYD88 L265P mutation in Diffuse Large B-cell Lymphoma (DLBCL).
• To assess the specificity of MYD88 L265P mutations for non-germinal center B-cell (non-GCB) DLBCL phenotypes and extranodal tumor sites.

Main Methods:

• Analysis of MYD88 L265P mutation using allele-specific PCR (AS-PCR) on DNA from FFPE tissues.
• Correlation of mutation status with histopathological subtype, immunophenotype, Cell of Origin (COO) classification via IHC, tumor site, and genetic features.
• Study cohort included 249 small B-cell lymphomas and 204 DLBCL cases.

Main Results:

• The MYD88 L265P mutation was detected in 32% of DLBCL cases.
• The mutation showed significantly higher prevalence in non-GCB DLBCL (OR 5.78, p=2.07×10⁻⁵) and extranodal DLBCL (OR 5.44, p<0.001).
• Affected extranodal sites included skin, breast, upper respiratory tract, adrenal gland, bone, and soft tissues.

Conclusions:

• The MYD88 L265P mutation is highly specific for the non-GCB DLBCL subtype.
• Its prevalence in extranodal sites suggests a role in the pathogenesis of these lymphomas, potentially reflecting MCD/C5 genetic features.