Expression of Bcl-2 Oncogene Product in Primary Non-Hodgkin's Malignant Lymphoma of the Oral Cavity

Abstract

The B-cell leukemia/lymphoma-2 (bcl-2) proto-oncogene is peculiar, as its product appears to provide survival advantage to B cells by blocking apoptosis. Expression of bcl-2 protein was analyzed in 54 cases of primary non-Hodgkin's malignant lymphomas of the oral cavity by immunohistologic staining of paraffin-embedded tissue. The immunophenotype of each tumor was established with the use of a panel of monoclonal and polyclonal antibodies to lymphoid cell differentiation antigens. The cases in the present study were 42 B-cell lymphomas, 7 T-cell lymphomas and 5-lymphomas revealing histiocytic markers. Sixteen of the 42 B-cell lymphomas were positive for bcl-2 protein, and were composed of 7 low-grade B-cell lymphomas and 9 high-grade B-cell lymphomas. Seven low-grade B-cell lymphomas were composed of one mucosa-associated lymphoid tissue type, three centrocytic types and three centroblastic-centrocytic types. Nine high-grade B-cell lymphomas comprised four centroblastic types, one immunoblastic type and four lymphoblastic types. Enhanced expression of the bcl-2 oncogenic protein was detectable in lymphoma cells in 2 cases for the T-cell lymphoma, and one case for the true histiocytic lymphoma. In contrast to the previous reports of American node-based lymphomas, Japanese primary oral lymphomas in our series expressed a lower frequency of bcl-2 protein. Furthermore, the present study indicated that bcl-2 protein was expressed on a wide variety of B-cell lymphomas, T-cell lymphomas and true histiocytic lymphoma, and that differences in bcl-2 protein expression may be useful in the diagnostic separation of lymphoblastic lymphoma with B-cell marker from Burkitt's lymphoma.