Monoclonal immunoglobulin production is a frequent event in patients with mucosa-associated lymphoid tissue lymphoma.

PURPOSE Mucosa-associated lymphoid tissue (MALT) lymphoma comprises 7% of all newly diagnosed non-Hodgkin's lymphomas and is therefore among the most common lymphoma entities. Monoclonal gammopathy due to production of a monoclonal immunoglobulin by lymphoma cells is a well-known phenomenon associated with various types of B-cell non-Hodgkin's lymphomas. The objective of the present study was to evaluate the incidence and clinical relevance of paraprotein (PP) production in patients with MALT lymphoma. EXPERIMENTAL DESIGN Fifty two patients were prospectively evaluated with regard to differentiation of the MALT lymphoma cells, t(11;18) translocation, monoclonal immunoglobulin production, Helicobacter pylori (HP) status, stage, treatment, and clinical outcome. RESULTS Nineteen of 52 MALT lymphoma patients (36%) had PP (8 IgMkappa, 6 IgGkappa, 4 IgMlambda, and 1 IgAkappa). The histologic feature of plasmacytic differentiation correlated significantly with the production of PP (P = 0.001). No correlation was found between PP and clinical stage, HP status, and t(11;18) status. PP was, however, negatively associated with response to eradication of HP in gastric MALT lymphoma, and PP levels declined significantly in patients responding to chemotherapy or radiation. Importantly, both immunofixation and serum electrophoresis have to be performed to detect low PP levels. CONCLUSIONS In conclusion, PP levels may probably be used as a potential prognostic tool for response to HP eradication, and serial measurements may also allow for noninvasive assessment of response to radiation or chemotherapy in patients with MALT lymphoma.