Histopathology - Amyloidosis

Question 1

What is amyloidosis?

Answer 1

A multisystem disorder caused by abnormal folding of proteins that are deposited as amyloid fibrils in tissues, disrupting their normal function

Question 2

How many forms are there of amyloidosis?

Answer 2

20

Question 3

What are two features of amyloid proteins?

Answer 3

• Β pleated sheet structure
• Resistant to enzyme degradation

Question 4

What protein is associated with primary amyloidosis?

Answer 4

• AL Amyloid

Question 5

What are some features of primary amyloidosis (AL Amyloidosis)?

Answer 5

• Most common
• Deposition of Ig light chains
• Most have monoclonal Ig, free light chains in serum + urine (Bence Jones) + increased bone marrow plasma cells

Question 6

What is primary amyloidosis most associated with?

Answer 6

Multiple Myeloma (although most don’t have multiple myeloma)

Question 7

What protein is associated with secondary amyloidosos?

Answer 7

• AA Amyloid

Question 8

What are some features of secondary amyloidosis (AA amyloidosis)?

Answer 8

• Amyloid formed from serum amyloid A
• Serum amyloid A = acute phase protein
• Build-up occurs secondary to chronic infections / inflammation

Question 9

What conditions are associated with secondary amyloidosis?

Answer 9

Autoimmune diseases (60%):
- RA
- Ankylosing spondylitis
- IBD

Chronic infections:
- TB
- Osteomyelitis
- IVDU (skin infections)

Non-immune:
- Renal cell carcinoma
- Hodgkin’s lymphoma

Question 10

What is haemodialysis associated amyloidosis and its features

Answer 10

Deposition of beta2-microglobulin
- Usually occurs in someone with longstanding Chronic Renal Failure (esp. if on peritoneal dialysis)
- A/W: Carpal tunnel syndrome

Question 11

What is familial amyloidosis and its general features?

Answer 11

Most common = Familial Mediterranean Fever (AR)
- AA Amyloid
- Predominant renal deposition

Question 12

What are the clinical features of amyloidosis (caused by amyloid deposits in organs)?

Answer 12

• Kidney: NEPHROTIC SYNDROME (most common)
• Heart: RESTRICTIVE CARDIOMYOPATHY, conduction defects, HEART FAILURE, cardiomegaly
• Liver/Spleen: Hepatosplenomegaly
• Tongue: MACROGLOSSIA (10%)
• Neuropathies: (inc. Carpal Tunnel)

Question 13

What is the pathology of amyloidosis?

Answer 13

• Apple green birefringence with Congo red stain under polarised light