A 65-end-stage renal disease on hemodialysis for 12 years develops carpal tunnel syndrome and shoulder joint stiffness. Synovial biopsy shows Congo red-positive amyloid deposits. The precursor protein forming these fibrils is:

• A Serum amyloid A (SAA)
• B Immunoglobulin light chains (lambda/kappa)
• C Beta-2 microglobulin ✓
• D Transthyretin (prealbumin)

Explanation

Long-term hemodialysis leads to accumulation of beta-2 microglobulin, which is not cleared by standard dialysis membranes and deposits as amyloid in joints and carpal tunnel (dialysis-associated amyloidosis). SAA causes AA amyloidosis in chronic inflammation; light chains cause AL amyloidosis in plasma cell dyscrasias; transthyretin is seen in senile systemic amyloidosis.

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.