Case Report of 59-Year-Old Woman with Bilateral Upper Limb Musculoskeletal Amyloid, Initially Diagnosed as Rheumatoid Arthritis.

BACKGROUND Amyloid light-chain (AL) amyloidosis is usually due to deposition of immunoglobulin lambda light chains from plasma cells in patients with multiple myeloma. AL amyloid may involve the salivary glands, gastrointestinal tract, peripheral nerves, and skin. However, musculoskeletal amyloid and amyloid arthropathy are rare.