We have monitored a 66-year-old woman who was diagnosed with non-Hodgkin’s lymphoma (NHL) based on a biopsy of her right breast in June 2006. Her previous including family history was unremarkable. Following administration of the first two cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), she developed asymmetric arthritis that affected the distal interphalangeal joints, the left shoulder and ankles with achillodynia in July/August 2006. Of note, these manifestations emerged within the first 6–8 weeks following the first rituximab exposure. Initially, acute gouty arthritis was suspected following chemotherapy, but normal levels of uric acid were found. She did not respond sufficiently to non-steroidal anti-inflammatory drugs (NSAIDs) and allopurinole and her arthritis progressed. Subsequently, widespread arthritis and …