A patient on maintenance hemodialysis for 18 years develops chronic shoulder and hip pain, carpal tunnel syndrome, and radiographic lytic bone lesions. Biopsy material stained with Congo red shows apple-green birefringence. The amyloid fibril precursor protein in this setting is:

• A Beta-2 microglobulin ✓
• B Serum amyloid A
• C Immunoglobulin lambda light chain variable region
• D Transthyretin

Explanation

Dialysis-related amyloidosis is caused by deposition of beta-2 microglobulin, a component of MHC class I molecules that is normally cleared by glomerular filtration. In end-stage renal disease it accumulates, and long-term hemodialysis, which removes it poorly, allows deposition in joints, tendon sheaths, and bone, producing arthropathy, carpal tunnel syndrome, and lytic lesions. Serum amyloid A defines AA amyloidosis, light chains define AL amyloidosis, and transthyretin forms familial and senile systemic amyloid.

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.