t(11;18)(q21;q21)-positive Advanced-stage MALT Lymphoma Associated with Monoclonal Gammopathy : Resistance to Rituximab or Rituximab-containing Chemotherapy

Abstract

Here we describe two cases of mucosa-associated lymphoid tissue (MALT) lymphoma with monoclonal immunoglobulins (Igs). The first case was a 77-year-old man with primary lymphoma of the lung. Immunoelectrophoresis detected IgM-κ in serum and κ light chain excretion into urine. Three months after treatment with single-agent rituximab, a large amount of pleural fluid was found to have accumulated. The fluid contained CD5 -, CD10 -, CD19+ , CD38 + and CD138 -/+ lymphoma cells with lymphoplasmacytoid appearance. Although a small fraction of the cells were CD20 + , the majority of the lymphoma cells were negative and expressed surface-membrane IgM-κ at low levels. The cells possessed a karyotype of 46, XY, t(11;18)(q21; q21). The second case was a 55-year-old man who underwent total gastrectomy due to gastric perforation. Surgical specimens demonstrated the histopathological features of MALT lymphoma associated with plasma cell differentiation. The lymphoma cells had a 46, XY, t(11;18)(q21;q21) karyotype. Monoclonal Igs detected were serum IgA (M)-κ and urinary κ light chain. The patient was subsequently treated with six cycles of R-CVP (rituximab, cyclophosphamide, vincristine and prednisolone) ; however, serum monoclonal Ig levels were not affected. The lymphoma cells in both cases may have contained two populations, a rituximab-sensitive CD20 + population and a rituximab-resistant population that had differentiated into the Ig-secreting plasma cell stage. 〔J Clin Exp Hematopathol 48(2) : 47-54, 2008〕

Coexistence of Mucosa-associated Lymphoid Tissue Lymphoma with Plasma Cell Features and Adenocarcinoma Cells in Pleural Fluid

“…A 59-year-old man presented with accumulation of pleural fluid. As reported previously in detail, 1 the patient first presented with gastric mucosa-associated lymphoid tissue (MALT) lymphoma eight years earlier, which responded to antibiotic therapy for the eradication of Helicobacter pylori (H. pylori). Three years before the current presentation, however, he underwent subtotal gastrectomy due to gastric perforation.…”

“…9 Other important points regarding this case were the plasma cell features and the diminished CD20 expression of the MALT lymphoma cells, in contrast to those of the excised stomach and the regional lymph node of three years earlier, both of which expressed CD20. 1 MALT lymphoma tissues include plasmacytoid cells with varying degrees of maturation, 10 and the disease is often associated with monoclonal gammopathy, 11 suggesting that MALT lymphoma cells have the potential to differentiate into the CD20plasma cell stage. This report supports the proposal that rituximab or rituximab-containing chemotherapy may promote the differentiation and/ or preferential proliferation of CD20cells, thereby causing the disease to be resistant to the immunochemotherapy.…”

“…This report supports the proposal that rituximab or rituximab-containing chemotherapy may promote the differentiation and/ or preferential proliferation of CD20cells, thereby causing the disease to be resistant to the immunochemotherapy. 1,12…”