CLINICOPATHOLOGICAL, ENZYME AND HISTOCHEMICAL-STUDIES OF CENTROCYTIC (MANTLE CELL) LYMPHOMA - COMPARISON WITH OTHER TYPES OF LOW-GRADE B-CELL LYMPHOMA BASED ON THE UPDATED KIEL CLASSIFICATION

Lymph nodes from 21 cases of malignant lymphoma of a centrocytic (mant le cell) type, (ML, cc (mc)) were examined. All the cases had monoclon al surface immunoglobulin (sIg) M and/or D, but were negative for CD10 (CALLA), and CD11c (LeuM5). Lymphoma cells with CD25 (anti-Tac)+, CD5 (Leu1)+, and alkaline phosphatase (ALPase)- in eight cases showed bon e marrow involvement (10-66% of the nucleated cells; mean 32 +/- 18%) but with no leukemic changes. These eight cases had a similar phenotyp e and were distributed by the lymphoma cells to the examined B-chronic lymphocytic leukemia, Seven cases showed an infiltration of CD25-, CD 5+, and ALPase- lymphoma cells, in which only two cases showed focal b one marrow involvement. There was a close relationship between CD25 ex pression 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 nuclei and a high anti-proliferat ing cell nuclear antigen/cyclin (PCNA/c) rate in the mantle zone and p aracortex, accompanied by a prominent interdigitating dendritic and hi stiocytic cell reaction. Examined CD25-, CD5-and ALPase+ lymphoma show ed a neoplastic counterpart of so-called marginal zone lymphocytes, wh ich was different from other cases of ML, cc (mc). Lymphoma cells in M L, cc (mc), except for those of the so-called marginal zone lymphoma, might be derived from sigM+, D+/-, CD25+/-, CD5+/-, ALPase-, CD10- and CD11c- lymphocytes present in the mantle zone and primary lymph folli cles. Other types of low-grade B cell neoplasms that were examined had different tumor cell markers for Ig, CD5, CD10, CD11c, a higher PCNA/ c rate, and prominent dendritic cells and histiocytic reaction when co mpared with those of ML, cc (mc).