Myositis Flashcards
(12 cards)
Describe anti-synthetase syndrome
Anti-Jo1 (most common ab type)
PM > DM
Leads to INTERSTITIAL LUNG DZ (40-60%)
List four types of myositis
- Polymyositis
- Inclusion Body Myositis
- Dermatomyositis
- Necrotizing autoimmune myositis
Cardinal feature of myositis
Proximal muscle WEAKNESS
- Often DYSPHAGIA
Describe necrotizing autoimmune myositis and its relation to statin-induced myopathy.
- Congophilic amyloid deposits
- Distal Muscle Weakness
List a path and a clinical feature of inclusion body myositis that distinguishes it from polymyositis.
Path differences:
- IBM = no CD8+, mainly MACROPHAGES
- Complement Deposition on capillaries
- Antibodies
1. Anti-SRP
2. Anti-HMGCR (statin-induced autoimmunity) - Cardiac involvement
List four types of myositis
- Polymyositis
- Inclusion Body Myositis
- Dermatomyositis
- Necrotizing autoimmune myositis (usu. > 50 y/o)
List four types of myositis
- Polymyositis
- Inclusion Body Myositis
- Dermatomyositis
- Necrotizing autoimmune myositis (usu. > 50 y/o - most common myopathy in that age group)
Dermatomyositis pathophysiology
- Complement Mediated (C3) -> MAC (C5b-9) deposition on endomysial capillaries
- CD4+ and macrophages
- Perifascicular atrophy
- Minimal infiltration
Polymyositis pathophysiology
- Myocyte MHC I expression
- ER stress
- CD8+ cytolysis
- Expression of anti-synthetase Abs (PM > DM)
Treatment for Necrotizing Autoimmune Myositis
If:
1. anti-HMGCR: stop statin + long term immunosuppressive
Lab/procedural tests for suspicion of myositis
Lab Tests
- CK
- ALT/AST
- Myositis associated antibodies:
- ANA
- Anti-synthetase (anti-Jo1)
Procedural Tests
- Electromyography (should be ABNL)
- Nerve conduction velocity (should be normal)
- MUSCLE BX
- CXR or CT lung imaging
- CA screen
Treatment for PM, DM, and NAM
Corticosteroids +/- immunosuppressives
