A 58-year-old woman on long-term hemodialysis for chronic kidney disease develops bilateral carpal tunnel syndrome and shoulder pain. Imaging shows periarticular soft tissue and bone cystic lesions, and biopsy of wrist tissue reveals congophilic deposits. The amyloid fibril precursor protein is:

• A Transthyretin
• B Beta-2 microglobulin ✓
• C Immunoglobulin lambda light chain
• D Islet amyloid polypeptide

Explanation

Dialysis-associated amyloidosis arises because beta-2 microglobulin, the invariant light chain of MHC class I molecules, is normally cleared exclusively by glomerular filtration. In end-stage renal failure it accumulates, and in patients on long-term hemodialysis it deposits in osteoarticular structures, causing carpal tunnel syndrome, shoulder pain, and bone cysts. Transthyretin causes senile cardiac and hereditary amyloidoses, light chains cause AL disease, and islet amyloid polypeptide is seen in type 2 diabetes mellitus.

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.