Mantle-zone lymphoma. A pattern produced by lymphomas of more than one cell type

We analyzed the distribution and immunologic phenotype of the neoplastic cells in eight cases of mantle-zone lymphoma. Although in all the cases the follicle centers appeared reactive on routine histologic examination, polyclonal staining for immunoglobulin was found in the follicle centers in only five of the eight cases; in the other three cases the follicle centers were monoclonal. In three cases, the immunologic phenotype was that of centrocytic (diffuse small cleaved cell) lymphoma: IgM+IgD+B1+B2+Ia+Tl+. In one case the phenotype was that of a follicular (centroblastic/centrocytic) lymphoma: IgG+B1+B2+Ia+CALLA+. In the other four cases, the phenotype was IgM+B1+B2+ or B2-Ia+; this phenotype can be seen in diverse B cell lymphomas. The phenotype of normal mantle-zone cells (IgM+IgD+B1+B2+Ia+) was not reproduced by any of the lymphomas. A mantle-zone pattern may be produced by either follicular or diffuse lymphomas of predominantly small cleaved cell type, and does not indicate an origin from the cells of the normal mantle zone.