Myositis Flashcards
idiopathic inflammatory myopathies
rare autoimmune diseases usually presenting with progressive, symmetrical, proximal muscle weakness
idiopathic inflammatory myopathies are characterised by
elevated CK, abnormalities on MRI and evidence of an irritative pattern on EMG
definitive diagnostic test for idiopathies inflammatory myopathies
muscle biopsy
dermatomyositis clinical features
any age
F > M
proximal
CK+++ x50
dermatomyositis biopsy
perimysial and perivascular inflammation
dermatomyositis associations
malignancy
ILD
connective tissue disorders
calcinosis in children
polymyositis clinical features
adults
F > M
no rash
proximal
CK+++ x50
polymyositis biopsy
inflammation
surrounding and invading muscle fibres
polymyositis associations
interstitial lung disease
autoimmune ddisorders
cancer
inclusion body myositis (IBM) clinical features
elderly
M > F
no rash
finger flexors, knee extensors
dysphagia
CK+ x20
inclusion body myositis biopsy
rimmed vacuoles (inclusion bodies)
inflammation surrounding and invading muscle fibres
inclusion body myositis associations
autoimmune disorders
poorly responsive to immunosuppressant therapy
necrotising autoimmune myositis clinical features
adult and older
F > M
proximal
CK+ x10
necrotising autoimmune myositis biopsy
necrotic muscle fibres with absence of inflammation
necrotising autoimmune myositis
malignancy
connective tissue disease
drug induced
MRI for myositis
diffuse and patchy test to confirm diagnosis, exclude other conditions and distinguish dermatomyositis from polymyositis
anti synthetase antibodies
associated with a subgroup of polymyositis with high incidence of interstitial lung disease, mechanics hands and raynauds
anti signal recognition particle
strong association with aggressive necrotising myositis and poor response to steroid treatment
anti Mi-2 antibody
strong association with acute polymyositis and dermatomyositis with good response to treatment wth immunosuppressants
