diffuse large B-cell lymphoma
Summary
Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma in adults, characterized by an aggressive but potentially curable clonal proliferation of large B lymphocytes. It typically presents with a rapidly enlarging lymph node mass or extranodal disease, and is diagnosed via lymph node biopsy showing sheets of large atypical lymphoid cells effacing normal architecture. Treatment with R-CHOP chemoimmunotherapy achieves cure in a majority of patients.
Detail
DLBCL arises from germinal center or post-germinal center B cells and can occur de novo or via transformation from a low-grade lymphoma (e.g., follicular lymphoma, CLL - Richter transformation). It accounts for ~30-40% of non-Hodgkin lymphomas. Histologically, large B cells (larger than 2x normal lymphocyte size) diffusely efface nodal architecture; immunophenotype is typically CD19+, CD20+, CD79a+, with variable CD10, BCL6, MUM1 (used in Hans algorithm to classify germinal center vs. activated B-cell subtype, which has prognostic significance - GCB subtype has better prognosis). Genetic alterations include BCL2, BCL6, and MYC rearrangements; concurrent MYC and BCL2/BCL6 rearrangements define 'double-hit' lymphoma, which is more aggressive. Clinically, patients present with rapidly enlarging lymphadenopathy (often single node or extranodal site like GI tract, CNS, testis, or bone), B symptoms (fever, night sweats, weight loss) may be present. Elevated LDH reflects tumor burden/turnover. Staging uses Ann Arbor system with PET-CT. International Prognostic Index (IPI) - age, stage, LDH, performance status, extranodal sites - predicts outcomes. First-line treatment is R-CHOP (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, Prednisone); cure rate approximately 60-70%. Relapsed/refractory disease may be treated with salvage chemotherapy, autologous stem cell transplant, or CAR-T cell therapy (e.g., axicabtagene ciloleucel). Key associations: can arise from EBV in immunocompromised patients (post-transplant lymphoproliferative disorder), HIV-associated lymphoma, and can involve extranodal sites like CNS (primary CNS lymphoma, associated with immunosuppression).
Sources
- Robbins and Cotran Pathologic Basis of Disease
- First Aid for the USMLE Step 1
- UpToDate: Diffuse large B-cell lymphoma
- WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues
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