The 2022 WHO Classification of Lymphoid Neoplasms introduces significant updates, incorporating advances in molecular diagnostics, improved disease categorization, and new disease entities. Key revisions include:
Hierarchical Reorganization- The classification follows a hierarchical structure from broad categories (e.g., mature B-cell neoplasms) to specific subtypes (e.g., diffuse large B-cell lymphoma, NOS).
Diagnostic Criteria Updates- New classification defines "essential" and "desirable" diagnostic criteria.
New and Deleted Entities- New entities introduced
- Tumor-like lesions with B-cell predominance, including IgG4-related disease and different types of Castleman disease. B-ALL with TCF3::HLF fusion, a highly aggressive subtype.
- EBV-positive mucocutaneous ulcer, a distinct entity. Fibrin-associated large B-cell lymphoma and Fluid overload-associated large B-cell lymphoma.
- Primary large B-cell lymphoma of immune-privileged sites, encompassing CNS, vitreoretinal, and testicular lymphomas. EBV-positive nodal T- and NK-cell lymphoma.
- Cutaneous marginal zone lymphoma, now a distinct entity separate from MALT lymphoma.
- Entities deleted
- B-cell prolymphocytic leukemia (B-PLL) is no longer recognized as a distinct entity due to its heterogeneous nature.
- NK-lymphoblastic leukemia/lymphoma removed due to lack of distinct defining characteristics.
Other changes include refined subtypes and nomenclature changes, expanded consideration of immunodeficiency-related neoplasms, and updated genetic classifications.
These revisions reflect a more precise, hierarchical, and molecularly integrated approach, providing better diagnostic clarity and aiding in treatment selection. Although the updates incorporate molecular advancements, they still ensure accessibility in resource-limited settings.
