CYCLIN D1 IMMUNOHISTOCHEMICAL STAINING IS USEFUL IN DISTINGUISHING MANTLE CELL LYMPHOMA FROM OTHER LOW-GRADE B-CELL NEOPLASMS IN BONE-MARROW

The distinction between mantle cell lymphoma (MCL) and ether low-grade B-cell neoplasms is important because MCL has a more aggressive clini cal course. In bone marrow biopsy specimens, this distinction can be e specially difficult. We examined 70 bone marrow biopsy specimens invol ved by various B-cell lymphoid neoplasms to assess the utility of cycl in D1 immunostaining in distinguishing MCL from other B-cell lymphopro liferative disorders. We used a cocktail of two monoclonal anti-cyclin D1 antibodies and a heat-and sonication-induced epitope retrieval pro cedure, The neoplasms assessed included MCL (32 cases), small lymphocy tic lymphoma/chronic lymphocytic leukemia (18 cases), follicular lymph oma (11 cases), hairy cell leukemia (5 cases), splenic marginal zone l ymphoma (2 cases), and small lymphocytic lymphoma with plasmacytoid di fferentiation (2 cases). The diagnosis of MCL in bone marrow was confi rmed by review of the original diagnostic biopsy specimens along with additional data, such as immunophenotypic or molecular studies. Most M CL (23/32; 72%) cases expressed cyflin DI protein. In contrast, one ca se of small lymphocytic lymphoma/chronic lymphocytic leukemia (1/18; 6 %) and one case of hairy cell leukemia (1/5; 20%) expressed cyclin D1 protein. These findings demonstrate that immunostaining for cyclin D1 protein expression is useful in distinguishing MCL from other B-cell l ymphoid neoplasms in the bone marrow.