Clinical implications of nodal marginal zone B-cell lymphoma among Japanese: study of 65 cases

To clarify the clinical presentation and outcome of nodal marginal zone B-cell lymphoma (NMZBL), 65 Japanese patients with this disease were studied and compared with the published literature from western countries. The clinical findings of our 65 cases were similar to those of their cases in some aspects: (1) 58% of the patients were > 60 years old (median age, 64 years); (2) there was a slight female predominance; (3) 90% of the patients exhibited asymptomatic lymphadenopathy in the head and neck area; (4) only a minority of patients had B symptoms (6%) and poor performance status (8%); and (5) only 5% of patients were positive for M-protein. However, the 65 patients in this series exhibited relatively longer 5-year overall survival (85%) and failure-free survival (60%) than the NMZBL series published in western literature, suggesting that NMZBL should be classified as indolent lymphoma. Moreover, based on the histological findings, we further classified four histological subtypes as follows: (1) splenic type (n = 7); (2) floral type (n = 9); (3) mucosa-associated lymphoid tissue (MALT) type (n = 29); and (4) diffuse large B-cell lymphoma (DLBCL) + MALT type (n = 20). DLBCL + MALT type exhibited significantly poorer 5-year overall survival than the splenic variant. The recognition of DLBCL + MALT type appears important. No API2-MALT1 fusion transcript was detected in any of the 14 cases examined.