A patient with reactive (secondary, AA) amyloidosis has recurrent chronic infections. The amyloid protein deposited is derived from which precursor?
- A Serum amyloid A protein (SAA), an acute-phase reactant produced by the liver ✓
- B Immunoglobulin light chains (AL amyloid) from clonal plasma cells
- C Transthyretin (TTR), produced by hepatocytes and choroid plexus
- D Beta-2 microglobulin, derived from MHC class I molecules
Correct answer: A. Serum amyloid A protein (SAA), an acute-phase reactant produced by the liver
Explanation
Reactive systemic (AA) amyloidosis is caused by prolonged elevation of serum amyloid A (SAA), an acute-phase protein produced by the liver during chronic inflammation (TB, rheumatoid arthritis, bronchiectasis, osteomyelitis). SAA fragments are deposited as AA amyloid fibrils. AL amyloid is from plasma cell dyscrasias. TTR amyloid causes cardiac/neuropathic amyloidosis. Beta-2 microglobulin accumulates in dialysis-related amyloidosis.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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