amyloid deposits

[pathologyguy]

A 55-year-old diabetic man has a long history of renal failure. He is currently waiting for an organ for transplant, and has been on hemodialysis in the interim. If this man develops amyloid deposits around his joints, they are likely to be composed of which of the following substances?

A. Amyloid-associated protein
B. Amyloid light chains
C. Beta2 microglobulin
D. Calcitonin precursors
E. Prealbumin (transthyretin)

[Asclepius1]

Is it B. Amyloid light chains ? For some reason when I think of the kidneys, I think of Bence John protein

[BlakeH]

Answer is C. Amyloid associated with hemodyalisis is B2 microglobulin

[pathologyguy]

Good job, the answer is C.

The correct answer is C. Amyloid deposits appear similar by light and electron microscopy, but actually represent a heterogeneous population of proteins that have a common tertiary structure forming a beta-pleated sheet. Questions about the type of amyloid seen in different disease states (even though the type is usually not determined clinically) are favorites on examinations. Here are two tables to help you out:

Systemic amyloidosis:
Chronic active disease AA amyloid from serum amyloid- associated (SAA) protein from liver (choice A)
Myelomas and related diseases AL amyloid from immunoglobulin light chain (choice B)
Chronic hemodialysis Beta2 microglobulin (related to high plasma levels) (choice C)
Nephropathic hereditary forms (familial Mediterranean fever) AA amyloid from SAA (choice A)
Cardiomyopathic hereditary forms (senile systemic amyloidosis) Prealbumin/transthyretin (choice E)
Neuropathic hereditary syndromes Prealbumin/transthyretin (choice E)



Localized amyloidosis:
Senile cardiac amyloidosis Atrial natriuretic peptide-related fibrils
Cerebral amyloid in Alzheimer disease, Down syndrome Cerebral amyloid in Alzheimer disease, Down syndrome
Medullary carcinoma of thyroid Calcitonin precursors (choice D)
Isolated, massive, nodular deposits (skin, lung, urogenital tract) AL from light chains (choice B)