Marginal Zone B-Cell Lymphoma: A Clinical Comparison of Nodal and Mucosa-Associated Lymphoid Tissue Types

Abstract

PURPOSE: In the International Lymphoma Study Group classification of lymphoma, extranodal marginal zone B-cell lymphoma (MZL) of mucosa-associated lymphoid tissue (MALT) type is listed as a distinctive entity. However, nodal MZL is listed as a provisional entity because of questions as to whether it is truly a disease or just an advanced stage of MALT-type MZL. To resolve the issue of whether primary nodal MZL without involvement of mucosal sites exists and whether it is clinically different from extranodal MALT-type lymphoma, we compared the clinical features of these two lymphomas. PATIENTS AND METHODS: Five expert hematopathologists reached a consensus diagnosis of MZL in 93 patients. Seventy-three were classified as having MALT-type MZL because of involvement of a mucosal site at the time of diagnosis, and 20 were classified as having nodal MZL because of involvement of lymph nodes without involvement of a mucosal site. RESULTS: A comparison of the clinical features of nodal MZL and MALT-type MZL showed that more patients with nodal MZL presented with advanced-stage disease (71% v 34%; P = .02), peripheral lymphadenopathy (100% v 8%; P < .001), and para-aortic lymphadenopathy (56% v 14%; P < .001) than those with MALT-type MZL. However, fewer patients with nodal MZL had a large mass (≥ 5 cm) than those with MALT-type MZL (31% v 68%; P = .03). The 5-year overall survival of patients with nodal MZL was lower than that for patients with MALT-type MZL (56% v 81%; P = .09), with a similar result for failure-free survival (28% v 65%; P = .01). Comparisons of patients with International Prognostic Index scores of 0 to 3 showed that those with nodal MZL had lower 5-year overall survival (52% v 88%; P = .025) and failure-free survival (30% v 75%; P = .007) rates than those with MALT-type MZL. CONCLUSION: Nodal MZL seems to be a distinctive disease entity rather than an advanced stage of MALT-type MZL because the clinical presentations and survival outcomes are different in these two types of MZL. Clinically, nodal MZL is similar to other low-grade, node-based B-cell lymphomas, such as follicular and small lymphocytic lymphomas.