Fogo, Ch. 18 - Amyloidosis

Question 1

What substances comprise amyloid?

Answer 1

Light chains (AL) or even heavy chains in fibrils.

Others: AA, ApoA1, ApoA-IV, transthyretin, fibrinogen, beta2-microglobulin.

Question 2

How does amyloidosis present?

Answer 2

Proteinuria. Half of patients have renal insufficiency.

Question 3

What is the difference between vascular and interstitial amyloid deposition in the kidney?

Answer 3

Interstitial amyloid usually causes renal insufficiency, whereas vascular can be silent.

Question 4

What are the LM findings in amyloidosis?

Answer 4

Amorphous acellular, pale eosinophilic material in the glomerular capillary walls and often in arterioles & arteries.

Question 5

Describe the staining properties of amyloid.

Answer 5

Usually PAS-. Can be silver+? Congo red+.

Question 6

Describe the IF findings in amyloidosis.

Answer 6

Smudgy positivity to usually lambda-light chain.

Question 7

Describe the EM findings in amyloidosis.

Answer 7

Randomly arranged, non-branching 10-12nm fibrils.

Question 8

What is the pathogenesis of amyloidoss?

Answer 8

Deposition of poorly degradable insoluble fibers (usually lambda light chains) in pleated beta sheets. Especially affects the glomerulus.

Question 9

How common is hereditary amyloidosis? How is it characterized?

Answer 9

10% of cases are hereditary.

No IF (not AL or AA proteins, maybe transthyretin).

Question 10

What is the relationship between amyloidosis and myeloma?

Answer 10

10% of patients with myeloma will manifest renal amyloidosis.

20% of patients with renal amyloidosis have myeloma.