A case of effective tocilizumab for arthropathy due to dialysis-related amyloidosis

A 79-year-old male patient on hemodialysis for 29 years was admitted to the hospital with unexplained fever (C-reactive protein, 16.1 mg/dL), anemia (hemoglobin 7.6 g/dL), and multiple joint swelling that began 7 months earlier. Infection was ruled out, both rheumatoid factor and anti-cyclic citrullinated peptide antibodies were negative. Positron emission tomography-computed tomography showed positive findings in bilateral shoulder joints, palmar region, femoral head area, and cervical spine. Magnetic resonance imaging showed low intensity on T1 and low-normal intensity on T2, especially in the shoulder joint. Musculoskeletal ultrasound revealed hypoechoic material with surrounding fluid collection and Doppler signals indicating blood flow in the shoulder joint, resembling synovitis associated with rheumatoid arthritis. Biopsy of the shoulder joint mass showed positive Congo-red and direct fast scarlet staining, positive β2-microglobulin, and infiltration of CD68-positive macrophages. Given the history of previous carpal tunnel release and cervical destructive spondyloarthropathy, dialysis-related amyloidosis, and amyloid-related arthritis were diagnosed. However, as the case had the feature of rheumatoid arthritis-like synovitis, tocilizumab was initiated, resulting in improved anemia and Clinical Disease Activity Index. We speculate that dialysis-related amyloidosis can present with arthritis involving cytokines, similar to rheumatoid arthritis, and tocilizumab may be effective for the resulting synovitis.