Inflammatory Myopathies

Question 1

Why is inflammatory myopathy thought to have an autoimmune origin?

Answer 1

1. Seen with other AI diseases
2. Pathology sugggests AI muscle cell injury
3. Serum Abs detected
4. Polymyositis and dermatomyositis respond to immunosuppresive Tx

Question 2

What are the most common morphologic characterisitics in inflammatory myopathies

Answer 2

1. Inflamm cells
2. Necrosis and phagocytosis of muscle fibers
3. Mixture of atrophic and regenerating fibers
4. fibrosis

Question 3

What are typical clinical findings in inflammatory myopathies?

Answer 3

Insidious proximal and symmetric muscle weakkness

Question 4

How is dermatomyositis distignuished from the other myopathies?

Answer 4

Charactersitic rash on upper eyelids, face trunk, and occasionally elsewhere. Can also be associated with scleroderma

Question 5

What are histologic findings in polymyositis? What Abs can be present?

Answer 5

Muscle fibers are surrounded by CD8+ T lymphocytes and macrophages; Muscular expression of MHCI; anti-Jo-1 and anti histidyl-transfer-RNA synthetase

Question 6

Is angiopathy found in polymyositis?

Answer 6

No

Question 7

A Congo red positive biopsy also contained Beta-amyloid deposits. What is the Dx?

Answer 7

Inclusion Body Myositis;

Question 8

What are the 4 characteristics of dermatomyositis?

Answer 8

1. Deposition of immune complexes in walls of capillaries/other BVs
2. Microangiopathy
3. Injury/atrophy of muscle fibers
4. Perivascular infiltrates of B cells and CD4+ T cells

Question 9

What clinically distinguishes dermatomyositis from other inflammatory myopathies? What whis the T cell ratio in dermatomyositis?

Answer 9

Rash!; High CD4 helpers:Low CD8+ cytotoxics