Inflammatory Myopathy Flashcards
What are the 5 classifications of inflammatory myopathy?
Dermatomyositis Polymyositis Inclusion body myositis Necrotizing myositis Anti-synthetase syndrome
What is the pattern of CK level across the types of inflammatory myopathies?
High CK- AS, NM
Moderate CK- DM, PM
Normal- DM
What is classic EMG finding for inflammatory myopathy?
“Irritable” myopathy
What are extra-muscular manifestations of DM?
Gottron’s papules Heliotrope erythema in eyelids Rash (face, chest, shoulders, arms, thighs) Interstitial lung disease Skin ulcers Arthritis Calcinosis (juvenile NXP-2)
AS syndrome has what extra-muscular manifestations?
Interstitial lung disease
“Mechanic hands”
Raynaud’s
What are major and minor criteria for AS syndrome?
Major: myopathy, ILD
Minor: mechanic hands, raynaud
Need positive antibody plus either 2 major or 1 major and 2 minor criteria
What antibody most commonly associated with AS syndrome?
Anti-Jo-1 antibody
What antibody is common in testing for sIBM?
Anti-NT5C1A antibody (70% sensitive, 90% specific)
What muscle is usually chosen for biopsy in suspected sIBM?
Vastus lateralis
What are characteristic features of sIBM on muscle biopsy?
Endomysial inflammation
Mitochondrial abnormality
Rimmed vacuoles
Chronic, active changes
What antibodies are associated with NM?
Anti-SRP
Anti-HMG CoA reductase
What types of NM is the risk of cancer increased?
Seronegative
Anti-HMGCR
What are classic findings of NM on muscle biopsy?
Randomly scattered necrotic fibers
Absence of significant inflammation
Scattered MHC1 expression
