Pathology Cheat Sheet
When Protein Becomes Deposit
Amyloidosis for NEET-PG: AL vs AA vs ATTR vs beta-2 microglobulin, Congo red apple-green birefringence, sago spleen, and renal nephrotic involvement here.
MedNext Academy | 3 min read
When Protein Becomes Deposit
Amyloidosis for NEET-PG: AL vs AA vs ATTR vs beta-2 microglobulin, Congo red apple-green birefringence, sago spleen, and renal nephrotic involvement here.
The pathogenesis, classification, and specimen recognition of amyloidosis, a shared tissue reaction of misfolded fibrillar protein.
High-yield lines
- Amyloid is extracellular deposition of misfolded protein arranged in a beta-pleated-sheet configuration.
- Amyloid stains pink-red with Congo red and shows pathognomonic apple-green birefringence under polarised light.
- AL amyloid is derived from immunoglobulin light chains (lambda more than kappa) and is linked to plasma cell dyscrasias such as multiple myeloma.
- AA amyloid is derived from serum amyloid A, an acute-phase reactant, and complicates chronic inflammation such as tuberculosis, leprosy, and rheumatoid arthritis.
- AA amyloidosis is especially common in India because of the high burden of tuberculosis and chronic suppurative disease.
- ATTR amyloid is derived from transthyretin and causes senile cardiac amyloidosis or hereditary familial amyloid polyneuropathy.
- Beta-2 microglobulin amyloid accumulates in long-term dialysis patients and causes carpal tunnel syndrome and arthropathy.
- Serum amyloid P component, apolipoprotein E, and heparan sulfate stabilise amyloid fibrils against degradation.
- Amyloid fibrils on electron microscopy are non-branching and 7 to 10 nm in diameter.
- The kidney is the organ most commonly affected in AA amyloidosis, presenting as nephrotic syndrome.
- The spleen shows a sago pattern with follicular deposits or a lardaceous pattern with diffuse red pulp involvement.
- AL amyloid characteristically causes macroglossia, cardiac involvement, and periorbital pinch purpura.
Mapped competency codes
- PA3.1
- PA3.2
Continue into the full chapter
This summary maps to PA3-amyloidosis.
Frequently Asked Questions
What is the confirmatory stain for amyloid?
Congo red, which stains deposits pink-red on light microscopy and produces apple-green birefringence under polarised light.
Which amyloid type is associated with chronic tuberculosis in India?
AA amyloid, derived from the acute-phase reactant serum amyloid A that stays elevated in chronic infection and inflammation.
Which amyloid type is linked to multiple myeloma?
AL amyloid, formed from immunoglobulin light chains produced by clonal plasma cells.
What amyloid type complicates long-term dialysis?
Beta-2 microglobulin amyloid, which deposits in periarticular tissue and causes carpal tunnel syndrome and destructive arthropathy.
Continue reading
Cheat SheetsAll Pathology cheat sheets
Browse the complete authored set for this subject.
Open the complete revision pathway
Explore clinician-written learning resources, structured revision and practice across the MedNext platform.
Open in the MedNext appSee plans

