Polyarthritis is a common manifestation of rheumatologic disorders; however, paraneoplastic arthropathies also arise as polyarthritis or polymyalgia, particularly in patients with myelomas, lymphomas, acute leukemia, and solid tumors. Because paraneoplastic syndromes, in some instances, might be manifested before a cancer diagnosis, they are difficult to diagnose and are often misdiagnosed. We experienced a 63-year-old female patient who had nonspecific arthritis on both hands and feet accompanied by fever. She had been diagnosed as rheumatoid arthritis and treated with prednisolone and disease modifying anti-rheumatic drugs (DMARDs) including methotrexate and anti-tumor necrosis factor agents. Her arthritis did not respond with anti-rheumatic treatment and diffuse large B-cell lymphoma was diagnosed by bone marrow biopsy. After 6 cycles of chemotherapy, her arthritis was improved as well as underlying lymphoma.

Keywords: Paraneoplastic syndromes, Diffuse large-cell lymphoma, Rheumatoid arthritis