[New classifications of malignant lymphomas - What changes are relevant for practice?]

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• Harmonizing lymphoma classification is crucial for clinical study comparability.
• Current landscape features two parallel systems: the International Consensus Classification (ICC) and the WHO classification (WHO-HAEM5).
• Specific entities like Follicular Lymphoma 3B and lymphoplasmocytic lymphoma (LPL) have adjusted diagnostic criteria.

Purpose of the Study:

• To compare and contrast the diagnostic criteria and implications of the ICC and WHO-HAEM5 classifications.
• To highlight key differences in classifying specific lymphoma subtypes, such as Follicular Lymphoma 3B and LPL.
• To emphasize the importance of molecular testing and distinct therapeutic considerations for certain lymphomas.

Main Methods:

• Comparative analysis of the ICC and WHO-HAEM5 lymphoma classification systems.
• Review of diagnostic criteria adjustments for entities including LPL and Follicular Lymphoma 3B.
• Examination of therapeutic implications stemming from classification differences, particularly for aggressive B-cell lymphomas and T-cell lymphomas.

Main Results:

• Follicular lymphoma 3B is separately classified as follicular large cell lymphoma in WHO-HAEM5.
• Both classifications recommend molecular testing for MYD88 and CXCR4 mutations in LPL.
• ICC groups NLPBL and THRLBCL within large B-cell lymphomas (LBCL), necessitating specific therapeutic strategies distinct from DLBCL.

Conclusions:

• The ICC and WHO-HAEM5 present distinct approaches to lymphoma classification, impacting specific subtypes.
• Molecular testing is increasingly vital for accurate LPL diagnosis.
• Therapeutic strategies for lymphomas like NLPHL/NLPBL and THRLBCL require careful consideration due to classification differences and distinct clinical behaviors compared to DLBCL.