Amyloidosis: True/False Statements
Statement-by-Statement Analysis
1. Characterized by the presence of extracellular basophilic hyaline material
FALSE - Amyloid deposits appear as eosinophilic (pink), not basophilic (blue), hyaline material on routine hematoxylin and eosin staining 1, 2, 3. This is a critical histopathological distinction that prevents misdiagnosis.
2. May be demonstrated by Congo red dye which stains the amyloid orange
FALSE - Congo red stains amyloid red (not orange) under normal light, and the pathognomonic finding is apple-green birefringence under polarized light 4, 5. This characteristic apple-green birefringence is the gold standard for identifying amyloid deposits and is essential for diagnosis 4.
3. Is deposited particularly in the spleen
TRUE - The spleen is indeed a common site of amyloid deposition in systemic amyloidosis 4, 1. Systemic light chain amyloidosis demonstrates protein affinity for visceral organs including kidney, heart, liver, and spleen, causing related end-organ dysfunction 4.
4. Is often found extensively in medullary carcinoma of the thyroid
TRUE - Medullary carcinoma of the thyroid is classically associated with extensive amyloid deposition within the tumor stroma. This represents localized amyloid formation from calcitonin-derived amyloid protein, which is a well-recognized histopathological feature of this specific thyroid malignancy.
5. May be a complication of Hodgkin's disease
TRUE - Secondary (AA) amyloidosis is associated with chronic inflammatory, infectious, and neoplastic diseases 1. Hodgkin's lymphoma, as a chronic neoplastic condition with inflammatory components, can lead to AA amyloidosis through sustained elevation of serum amyloid A protein 1, 2. This represents reactive amyloidosis secondary to the underlying malignancy.
Key Diagnostic Pitfalls
- Do not confuse eosinophilic with basophilic staining - this fundamental error can lead to missing the diagnosis entirely 1, 2
- Always confirm with polarized light microscopy - the apple-green birefringence is pathognomonic and cannot be substituted 4, 5
- Remember that amyloid typing by mass spectrometry is the gold standard with 88% sensitivity and 96% specificity, as immunohistochemistry alone can be misleading 4