Proliferation centres in B-cell malignant lymphoma, lymphocytic (B-CLL): an immunophenotypic study

Area of Science:

• Hematology
• Oncology
• Immunohistochemistry

Background:

• Proliferation centres, or pseudofollicles, are characteristic of B-cell chronic lymphocytic leukemia (B-CLL), found in ~90% of cases.
• These structures differ from true B-cell follicles, with prior uncertainty regarding follicular dendritic cell presence.

Purpose of the Study:

• To investigate the immunohistochemical characteristics of proliferation centres in B-CLL.
• To compare proliferation centres with surrounding lymphocytic infiltrate and entrapped reactive B-cell follicles.

Main Methods:

• Immunohistochemical analysis of 30 B-CLL lymph node specimens.
• Comparison of proliferation centres, surrounding infiltrate, and reactive follicles for follicular dendritic cells, IgM, complement, proliferation fraction, T-cells, and bcl-2 expression.

Main Results:

• Most proliferation centres exhibited a delicate follicular dendritic cell network with IgM and complement, higher proliferation rates, more T-cells, and decreased bcl-2 expression compared to the surrounding infiltrate.
• Entrapped reactive B-cell follicles showed denser follicular dendritic cell networks, stronger IgM/complement expression, very high proliferation rates, abundant T-cells, and minimal bcl-2 expression.

Conclusions:

• Proliferation centres in B-CLL possess distinct immunohistochemical features, including the presence of follicular dendritic cells and elevated T-cell infiltration.
• These findings contribute to understanding the microenvironment and cellular dynamics within B-CLL, differentiating them from reactive B-cell follicles.