A patient with chronic renal failure on long-term hemodialysis develops carpal tunnel syndrome and arthropathy. Congo red staining of the joint biopsy shows apple-green birefringence. What is the amyloid fibril protein responsible?

• A AL amyloid from monoclonal immunoglobulin light chains
• B Aβ2M amyloid from beta-2 microglobulin accumulation in dialysis patients ✓
• C AA amyloid from serum amyloid A protein in chronic inflammation
• D ATTR amyloid from transthyretin in senile cardiac amyloidosis

Explanation

Dialysis-related amyloidosis (DRA) is caused by beta-2 microglobulin (β2M) that accumulates in patients on long-term hemodialysis, as it is not adequately cleared by conventional dialysis membranes. β2M fibrils preferentially deposit in the carpal tunnel, synovial tissue, and bone, causing carpal tunnel syndrome, arthropathy, and destructive spondyloarthropathy. The Aβ2M designation distinguishes it from AL (primary), AA (reactive), and ATTR (senile/hereditary) amyloidosis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.