Objective: Amyloid deposition in multiple myeloma (MM) may lead to an arthropathy resembling
rheumatoid arthritis (RA). Since a systematic description of its natural history is lacking, we have
performed a systematic analysis of all published cases.
Methods: Literature review featuring backward and forward database searches and direct inspection of
reference lists. Inclusion criteria were as follows: publication between 1931 and 2012, diagnosis of
multiple myeloma, and demonstration of light chain amyloid (AL) in any organ or in synovial fluid,
arthritis, or synovitis.
Results: Overall, 101 cases were identified. Median age was 59 years and the male-to-female ratio was
1:1. A systemic manifestation of MM was reported in 88 cases. In 53 of these, characteristic physical
findings (carpal tunnel syndrome, macroglossia, shoulder pad, and soft tissue swelling/masses) were
present. Arthritis manifested before the diagnosis of MM in 63 cases, with 33 cases initially misdiagnosed
as RA. There were 72 cases of poly-, 17 of oligo-, and three of monoarthritis. The shoulder joint was most
commonly affected, followed by knees and small hand joints. Median synovial fluid leukocyte count was
2460 cells/mm3, and was normal in seven cases. Synovial histopathology often featured mild synovitis
without plasma cell infiltration. Imaging revealed articular or periarticular inflammation in many cases
and bone lesions near 22% of affected joints. Treatments varied but led to some improvement in the
majority of cases.
Conclusions: These results solidify previous experience that MM arthropathy tends to feature a
symmetric RF-negative nonerosive polyarthritis. However, the results also highlight the diversity of its
presentations and stress the importance of arthropathy as a potentially under-recognized presenting
manifestation of MM.