Clinical features of patients with nodal marginal zone lymphoma compared to follicular lymphoma: similar presentation, but differences in prognostic factors and rate of transformation.

Nodal marginal zone lymphoma (NMZL) is a rare type of B-cell non-Hodgkin lymphoma. This study assessed the clinical features of 56 patients with NMZL in comparison to 46 patients with follicular lymphoma (FL). Patients with NMZL and FL had a largely similar clinical presentation, but patients with FL had a higher disease stage at presentation, more frequent abdominal lymphadenopathy and bone marrow involvement, and showed more common transformation into diffuse large B-cell lymphoma (DLBCL) during the course of disease. Overall survival and event-free survival were similar for patients with NMZL and FL, but factors associated with worse prognosis differed between the two groups. Transformation into DLBCL was associated with a significantly poorer outcome in both groups, but the phenotypes were different: DLBCL arising in FL was mainly of germinal center B-cell phenotype, whereas DLBCL arising in NMZL was mainly of non-germinal center B-cell phenotype.