A 52-year-old woman on long-term maintenance hemodialysis for chronic kidney disease develops chronic shoulder pain and a carpal tunnel syndrome that fails surgical release. Imaging shows juxta-articular bone cysts. Biopsy of the synovium shows amorphous deposits staining with Congo red and showing apple-green birefringence. The fibril precursor protein is:

• A Serum amyloid A produced by the liver
• B Beta-2 microglobulin derived from MHC class I molecules ✓
• C Transthyretin synthesized by the liver and choroid plexus
• D Immunoglobulin lambda light chain variable region

Explanation

Dialysis-related amyloidosis occurs when beta-2 microglobulin, normally cleared by glomerular filtration, accumulates in patients without residual renal function. It deposits in osteoarticular structures, causing carpal tunnel syndrome, shoulder pain, and lytic bone lesions. Serum amyloid A defines reactive AA amyloidosis, light chains define AL amyloidosis, and transthyretin causes senile cardiac and familial forms, none of which track with dialysis vintage.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.