The coexistence of non-Hodgkin´s lymphoma and multiple myeloma is very rare and the coexistence of nasal NK/T-cell lymphoma and multiple myeloma has never been reported in the literature. Recently, a 63-year-old woman was presented with small amount of hematemesis. Bone marrow showed increased immature plasma cell (72.5%). Serum protein electrophoresis showed monoclonal gammopathy (6.5g/dL). Serum immunoelectrophoresis showed IgG and kappa type monoclonality. Microscopic examination of left nasopharynx and inferior turbinate revealed nasal NK/T-cell lymphoma. Six cycles of CHOP (cyclophosphamide, daunomycin, vincristine, prednisone) chemotherapy induced the complete remission of both tumors, but died of cerebral involvement of NK/T-cell lymphoma in 12 months after the diagnosis.

Keywords: Coexistence, Multiple Myeloma, Nasal NK/T-cell lymphoma, Non-Hodgkin´s Lymphoma