What are the pathologic characteristics of DLBCL?

Updated: Jun 12, 2019
  • Author: Shipra Gandhi, MBBS; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Morphologically, DLBCL is composed of large B cells with a high proliferation index resembling germinal centroblasts. DLBCL usually develops de novo but can also emerge as a clonal transformation in patients with low-grade lymphomas or chronic lymphocytic leukemia (CLL). De novo DLBCL tends to have a better response rate to standard therapy and better prognosis than transformed DLBCL. Several morphologic variants of DLBCL have been described, such as centroblastic, immunoblastic, plasmablastic, T-cell/histiocyte-rich, and anaplastic B-cell lymphoma (usually anaplastic lymphoma kinase [ALK]) positive). [31, 32] While each of these variants can be determined by pathological evaluation, the clinical prognostic significance remains controversial.

Immunophenotype studies demonstrate that DLBCL co-expresses pan B-cell markers, including CD19, CD20, CD79a, CD45RA, and the nuclear transcription factor PAX5. The expression of additional markers may have prognostic implications. The proliferation factor Ki67 is usually high, at 65% mean percentage. High Ki67 levels (>80%) have been associated with a shorter survival. [33] Germinal center–associated markers CD10 and Bcl-6 are expressed in approximately 30-40% and 60%, respectively. Bcl-6 expression has been associated with a prolonged progression-free survival (PFS) and overall survival (OS) following rituximab chemotherapy in retrospective studies. [34, 35] On the other hand, CD5 is expressed only in 10% of DLBCL cases, and its expression should raise the suspicion of transformation from a more indolent form of NHL such as small lymphocytic lymphoma (SLL) or CLL, and it has been associated with a shorter survival. [36]


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