title: 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-kappa in serum and kappa 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-kappa 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)-kappa and urinary kappa 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.
authors.affiliation: Department of Hematology, Takeda General Hospital, Kyoto, Japan. kitoshi-ono@fm2.seikyou.ne.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ohno
authors.forename: Kotaro
authors.initials: K
authors.lastname: Isoda
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20 / Q000096:biosynthesis; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002880:Chromosomes, Human, Pair 11; D002887:Chromosomes, Human, Pair 18; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000276:immunology; D018442:Lymphoma, B-Cell, Marginal Zone / Q000188:drug therapy* / Q000235:genetics* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010265:Paraproteinemias / Q000188:drug therapy* / Q000235:genetics*; D000069283:Rituximab; D014178:Translocation, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000970:Antineoplastic Agents; D000069283:Rituximab