Amyloid arthropathy: characterization of the amyloid protein.
An 82 year-old man was referred for joint pain and numbness of his hands. Physical examination revealed limitation of movement of the PIP's, MCP's, wrists, shoulders and knees. There was marked synovial thickening of the wrists and atrophy of the thenar muscles of both hands due to arpal tunnel syndrome. The patient was operated on both hands, the median nerves were released and a synovectomy of the wrist was performed. Two months later, a synovectomy of the right shoulder was performed. Histological examination of tissues from the wrists and shoulder demonstrated large deposits of amyloid in the synovia. Amyloid fibrils were extracted, solubilized in 6M and were fractionated on a Sepharose 6B. All three proteins that were purified from the amyloid fibrils proved to be derived from VkI light chain by their amino terminal sequences. This is the first amyloid protein to be characterized from amyloid arthropathy.