Inflammatory Myopathies

Dermatomyositis

 • Onset: Subacute

 • Pattern: Proximal

 • CK: Up to 50X ULN

 • Autoantibodies: Anti-MDA5, anti-Mi-2, anti-TIF-1, anti-NXP-2

 • Associated Features: Cancer-associated, periorbital heliotrope, shawl sign

Polymyositis

 • Onset: Subacute

 • Pattern: Proximal

 • CK: Up to 50X ULN

 • Autoantibodies: Anti-synthetase

 • Associated Features: Diagnosis of exclusion

Necrotizing Autoimmune Myositis

 • Onset: Acute or subacute

 • Pattern: Proximal

 • CK: >50X ULN

 • Autoantibodies: Anti-SRP, anti-HMGCR

 • Associated Features: Weakness is severe, initially worsens after offending med is discontinued

Inclusion Body Myositis

 • Onset: Insidious/slow

 • Pattern: Proximal and distal

 • CK: Up to 10x ULN

 • Autoantibodies: Anti-cN1A

 • Associated Features: Develops over years, often diagnosed when patients don't respond to steroids



- BWH Medicine Chiefs @BrighamChiefs



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