In WHO 2022 classification, Large B-cell lymphoma with IRF4 rearrangement was introduced as a distinct provisional entity. Which clinical and histological features distinguish it from diffuse large B-cell lymphoma (DLBCL), NOS?

• A It predominantly affects children and young adults, involves Waldeyer ring, shows follicular architecture at least focally, expresses IRF4/MUM1 and BCL6, and has an excellent prognosis ✓
• B It predominantly affects elderly patients, shows germinal center B-cell (GCB) phenotype by IHC, and carries poor prognosis with R-CHOP
• C It exclusively shows a non-GCB activated B-cell phenotype and is treated identically to double-hit DLBCL
• D It arises from transformation of follicular lymphoma and carries the same BCL2 translocation

Explanation

Large B-cell lymphoma with IRF4 rearrangement (WHO 2022) is a distinct entity predominantly affecting children, adolescents, and young adults. It frequently involves Waldeyer ring (tonsils) and cervical lymph nodes, shows at least partial follicular architecture, and co-expresses IRF4/MUM1 and BCL6 by IHC. Despite its large cell morphology, it carries an excellent prognosis with standard R-CHOP or even less intensive therapy. It is distinct from DLBCL arising from follicular lymphoma transformation (which retains BCL2 translocation) and is not preferentially double-hit.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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