Mantle cell lymphomas (MCLs) are typically CD5-expressing B-cell non-Hodgkin's lymphomas (NHLs) that frequently harbor the chromosomal translocation t(11;14) or bcl-1 gene rearrangements. Insufficient data are available on the biologic features and clinical behavior of rigorously characterized MCL. As these NHLs have been reported to exhibit various histologic and cytologic expressions, and in order to avoid using somewhat arbitrary and subjective morphologic definitions, we chose to study cases of MCL selected on more objective grounds. Specifically, 15 samples (from 14 patients) of CDS-expressing B-cell NHLs with detectable bcl-1 gene rearrangement were included. Overall, these patients had relatively uniform clinical manifestations. Most were older men (mean age, 67 years) who presented with lymphadenopathy, high-stage disease, and bone marrow involvement. All but two patients relapsed, demonstrated residual tumor, or had disease progression after an initial response to various therapies. Nine patients have died; these patients had a median survival of only 19 months. All cases could be classified within the broad morphologic spectrum previously described for MCL, and no predominant histologic subtype was observed. However, cases could be segregated into two major groups according to tissue architecture: one with a purely diffuse pattern and the other with at least a focal nodular component. Patients with purely diffuse tumors had a lower survival rate (0%) than those with tumors having a nodular component (62% survival rate). In contrast to the morphologic variability, these NHL exhibited a rather homogeneous immunophenotypic pattern. All cases demonstrated intense CD20 expression, with typically intense IgM and light chain expression, and relatively weak IgD expression. In no case was CD10 detected on the neoplastic cells. DNA content analysis showed aneuploidy only in three instances, and two groups of cases could be arbitrarily defined on the basis of their S-phase fraction. A relationship between a purely diffuse growth pattern and a high S-phase fraction (greater than 5%) was observed. As expected from this association, patients with tumors having high S-phase fractions fared worse (14% survival rate) than those patients with tumors showing lower S phase fractions (57% survival rate). Thirteen NHLs from 12 patients had amplifiable bcl-1 gene rearrangements at the major translocation cluster (MTC). The bcl-1 breakpoints aggregated within a 63-bp region of the MTC, and the amplified tumor DNA from each patient had unique N-nucleotide junctional sequences and lg joining region breakpoint sites. Two additional NHLs had bcl-1 gene rearrangements detected only with Southern blot hybridization using a genomic probe directed at a breakpoint site distant from the MTC. We conclude that CD5-expressing B-cell NHLs with bcl-1 gene rearrangement can be morphologically classified as MCL, have relatively uniform immuno-phenotypic characteristics, and are associated with an overall poor prognosis. Architectural growth pattern and kinetic information, such as S-phase fraction, may help separate a more aggressive group of these NHL from a relatively less aggressive subset. (C) 1995 by The American Society of Hematology.
