A patient on long-term hemodialysis for chronic kidney disease develops carpal tunnel syndrome and flexor tenosynovitis. Biopsy of the affected tendon sheath shows amorphous deposits staining with Congo red. The amyloid fibril protein in this setting is:

• A Beta-2 microglobulin ✓
• B Transthyretin
• C Serum amyloid A
• D Amylin (islet amyloid polypeptide)

Explanation

Beta-2 microglobulin, normally cleared by glomerular filtration, accumulates in patients on long-term dialysis and forms periarticular amyloid deposits causing carpal tunnel syndrome, shoulder pain, and bone cysts. Transthyretin causes senile cardiac and familial amyloid polyneuropathy, serum amyloid A underlies secondary inflammatory amyloidosis, and amylin deposits in pancreatic islets in type 2 diabetes.

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.