Abstract

There had been a continuous evolution of lymphoma classification and recently a Revised European-American Lymphoma Classification was proposed by the International Lymphoma Study Group. This new classification often requires information on immunophenotypic and molecular biologic markers in addition to the usual histologic findings. Recent advances in the production of commercially available monoclonal antibodies reactive on formalin-fixed paraffin-embedded tissues provide us a great help to classify the non-Hodgkin's lymphoma. We have analyzed 31 low grade B-cell lymphomas by the schemes proposed by the International Lymphoma Study Group using antibodies to CD3, CD5, CD20, CD23, CD43, cyclin D1, and bcl-2 protein, and have analyzed the immunophenotypic features. Among 31 low grade B-cell lymphomas, 8 small lymphocytic lymphomas, 5 mantle cell lymphomas, 7 follicle center lymphomas (2 grade I, 3 grade II, and 2 grade III), and 11 marginal zone B-cell lymphomas (all of which were extranodal) were identified. Among 8 small lymphocytic lymphomas, 5 cases were positive for CD5; 6 cases were positive for CD23; 7 cases were positive for CD43; all 8 cases were negative for cyclin D1; and 7 cases were positive for bcl-2. Among 5 mantle cell lymphomas, 4 cases were positive for CD5 and CD43; all five cases were negative for CD23; 4 cases were positive for cyclin D1 and bcl-2. All 7 follicle center lymphomas were negative for CD5, CD43 and cyclin D1 and 2 cases were positive for CD23; and 6 cases were positive for bcl-2. All marginal zone B-cell lymphomas were negative for CD5, CD23 and cyclin D1; 3 cases were positive for CD43 and 9 cases were positive for bcl-2. Diagnostic utility for CD5 antigen detection on paraffin embedded tissue has a limitation due to weak antigen expression in tumor cells of B-cell lymphomas; however, still be useful in differentiating small lymphocytic lymphoma and mantle cell lymphoma from other B-cell lymphomas when applied in conjunction with CD43. CD23, CD43, and cyclin D1 appear to be of great help in differentiating subgroups of low grade B-cell lymphomas. Bcl-2, as known, is found to be useful to rule out reactive follicular hyperplasia.

• Keywords: Malignant lymphoma;B-cell;CD5-23-43;Cyclin D1;Bcl-2