Large B-Cell Lymphoma with IRF4 Rearrangement

Large B-Cell Lymphoma with IRF4 Rearrangement (LBCL-IRF4) is a rare, distinct type of lymphoma recognised in the 2022 WHO classification. It is defined by a specific chromosomal change — usually the t(6;14)(p25;q32) translocation — that causes abnormal overexpression of the IRF4 protein in B-cells. It most commonly arises in the tonsil and Waldeyer's ring of children and young adults. Despite having some features that can appear aggressive under the microscope, it generally responds well to standard rituximab-based chemotherapy and carries a more favourable outlook than many other large B-cell lymphomas.

Although both are large B-cell lymphomas, LBCL-IRF4 is a molecularly and clinically distinct entity. It arises in younger patients, predominantly in the tonsil and Waldeyer's ring, and is defined by IRF4 gene rearrangement rather than the more varied genetic landscape of standard DLBCL. It also carries a generally more favourable prognosis. Importantly, distinguishing LBCL-IRF4 from DLBCL requires FISH testing — making specialist haematopathology review essential, as treatment can be appropriately calibrated to the lower-risk biology of this entity.

Diagnosis requires an adequate tissue biopsy (core needle or excision) with comprehensive haematopathology assessment. Immunohistochemistry showing strong MUM1/IRF4 protein positivity raises suspicion, but FISH for IRF4 rearrangement — confirming the chromosomal translocation — is mandatory for definitive diagnosis. Additional FISH studies for MYC and BCL2 are performed to exclude high-risk double-hit rearrangements. PET-CT is performed for staging, and bone marrow biopsy is generally included in the workup.

Treatment for LBCL-IRF4 is based on rituximab-containing immunochemotherapy — most commonly R-CHOP in adults or paediatric-adapted protocols such as LMB-based regimens for children. The number of treatment cycles depends on disease stage, typically three to six cycles. Response is assessed with interim PET-CT scanning. Selected patients with bulky or residual disease may receive involved-site radiotherapy as consolidation. Patients with relapsed or refractory disease may be considered for salvage chemotherapy, autologous stem cell transplantation, or CAR-T cell therapy.

Yes, many patients with LBCL-IRF4 — particularly those with localised disease — achieve durable complete remission with modern immunochemotherapy, and outcomes are generally more favourable than for standard DLBCL. Patients with advanced or relapsed disease face greater challenges, but advances in CAR-T cell therapy, bispecific antibodies, and salvage regimens continue to improve prospects. Individual prognosis depends on disease stage, molecular profile, and response to initial treatment.

Not always — and this is an important reason why paediatric haematology-oncology involvement is essential. While the general principle of rituximab-based immunochemotherapy applies across age groups, children and adolescents typically receive modified dosing and paediatric-adapted protocols that balance efficacy with reduced long-term toxicity (particularly for the heart, gonads, and growth). Specialist paediatric oncology centres with lymphoma expertise should be involved in treatment planning for all patients under 18, and ideally for young adults up to age 25–30.

Double-expressor means the lymphoma cells stain positively for both MYC and BCL2 proteins by immunohistochemistry — this is different from 'double-hit', which refers to concurrent gene rearrangements of MYC and BCL2/BCL6. Many LBCL-IRF4 cases are double-expressors without being double-hit. In LBCL-IRF4, this protein co-expression does not carry the same severe adverse prognosis as true double-hit lymphoma, but it warrants monitoring. Your haematopathologist and oncologist should clarify which category applies to your case.

Relapsed or refractory LBCL-IRF4 is treated similarly to other relapsed large B-cell lymphomas. Salvage immunochemotherapy regimens (such as R-ICE or R-DHAP) are used to achieve remission prior to autologous stem cell transplantation in eligible patients. CD19-directed CAR-T cell therapies (axicabtagene ciloleucel, tisagenlecleucel) are available for patients who relapse after two or more prior lines of therapy, and bispecific T-cell engagers (epcoritamab, glofitamab) offer additional options. Clinical trial enrolment is strongly encouraged at relapse.

Yes. CancerFax supports patients and families navigating LBCL-IRF4 by organising specialist haematopathology second opinions to confirm the diagnosis and molecular classification, coordinating access to advanced therapies including CAR-T cell programmes and bispecific antibody trials at leading centres in India and China, and facilitating cross-border treatment planning for patients seeking international options. Our team can review medical reports, identify eligible clinical trials based on your molecular profile, and connect you with paediatric and adult lymphoma specialists. Please submit your medical records through our upload portal to begin the process.