IMMUNOHISTOCHEMICAL ANALYSIS OF CYCLIN D1 PROTEIN IN HEMATOPOIETIC NEOPLASMS WITH SPECIAL REFERENCE TO MANTLE CELL LYMPHOMA

Immunohistochemical expression of PRAD1/cyclin D1 protein has been inv estigated in 106 tissue specimens of 104 cases of lymphoma, non-neopla stic lymphoid disorders and other hematologic malignancies by employin g the monoclonal antibody 5D4 with formalin-fixed paraffin-embedded se ctions, using the microwave oven heating method. Positive neoplastic c ells were found in 60 (74%) of 81 cases of non-Hodgkin's lymphoma. The positivity pattern was nuclear in 17 (85%) of 20 cases of mantle cell lymphoma in which cytoplasmic staining was also seen. This pattern of cyclin D1 positivity was in contrast to the negative staining of norm al reactive mantle zones. In the other cases, positivity appeared to l ie within the cell cytoplasm without nuclear staining, and most of the nodal follicular and diffuse B-cell lymphomas variously expressed PRA D1/cyclin D1. In contrast, the reaction was absent in a significant nu mber of T-cell and extranodal B-cell. lymphomas. Immunolocalization of PRAD1/cyclin D1 expression appears to be a useful diagnostic adjunct to discriminate mantle cell lymphoma from other non-Hodgkin's lymphoma s.