Clinicopathologic, enzyme and hisotchemical studies of centrocytic (mantle cell) lymphoma: Comparison with other types of low‐grade B cell lymphoma bases on the updated Kiel classification

Lymph nodes from 21 cases of malignant lymphoma of a centrocytic (mantle cell) type, (ML, cc (mc)) were examined. All the cases had monoclonal surface immunoglobulin (sig) M and/or D, but were negative for CD 10 (CALLA), and CD11c (LeuM5). Lymphoma cells with CD25 (anti‐Tac)+, CD5 (Leu1)+, and alkaline phosphatase (ALPase) ‐ in eight cases showed bone marrow involvement (10–66% of the nucleated cells; mean 32± 18%) but with no leukemic changes. These eight cases has a similar phenotype and were distributed by the lymphoma cells to the examined B‐chronic lymphocytic leukemia. Seven cases showed an infiltration of CD25 ‐ , CD5+, and AL Pase ‐ lymphoma cells, in which only two cases showed focal bone marrow involvement.There was a close relationship between CD25 expression and bone marrow invasion by the lymphoma cells in ML, cc(mc). Three of the six CD25 ‐ and CD5 ‐ cases presented zonal proliferation of AlPase+ lymphoma cells with round nuciee and a high anti‐proliferating cell nuclear antigen/cyclin (PCNA/c) rate in the mantle zone and paracortex, accompanied by a prominent interdigitating dendritic and histiocytic cell reaction. Examined CD25 ‐ , CD5 ‐ and ALPase+ lymphoma showed a neoplastic counterpart of so‐called marginal zone lymphocytes, which was different from other cases of ML, cc (mc). Lymphoma cells in ML, cc(mc), except for those of the so‐called marginal zone lymphoma, might be derived from slgM+, D+/ ‐ , CD25+/ ‐ , CD5+ /‐ , ALPase ‐ , CD10 ‐ and CD11c‐ lymphocytes present in the mantle zone and primary lymph follicles. Other types of lowgrade B cell neoplasms that were examined had different tumor cell markersfor ig, CD5, CD10, CD11c, a higher PCNA/c rate, and prominent dendritic cells and histiocytic reaction when compared with those of ML, cc (mc).