SM_246a: Inflammatory Myopathies Flashcards
Inflammatory myopathies are those where inflammatory response is directed against ____, ____, and ____
Inflammatory myopathies are those where inflammatory response is directed against normal muscle, supporting stroma, and muscle as one of many tissues
(all inflammation in muscle is NOT an autoimmune inflammatory myopathy)
Inflammatory myopathies include ____, ____, ____, and ____
Inflammatory myopathies include polymyositis, dermatomyositis, inclusion body myositis, and necrotizing autoimmune myopathy
- Dermatomyositis: adults with skin involvement, juvenile
- Necrotizing autoimmune myopathy: statin induced necrotizing myositis, signal reduction particle myopathy
Other sites thay may be involved in inflammatory myopathies are ____, ____, and ____
Other sites thay may be involved in inflammatory myopathies are skin, joint, and lung (ILD)
Take muscle biopsy from the ____ area on MRI
Take muscle biopsy from the white area on MRI
Describe clinical manifestations of polymyositis
Polymyositis
- Symmetric, proximal greater than distal
- Occasional mild facial weakness
- Can present with dysphagia
- Insidious but not hyperacute
- Myalgias
- Pulmonary involvement
- Anti-Jo-1: female more than male
- Constitutional symptoms including fever weight loss, and myalgias
- Rare myocarditis
- Polyarthralgias
Most important test for polymyositis is _____
Most important test for polymyositis is creatine kinase
- Serologic tests: ESR, ANA w/ autoimmune pannel, CRP, myositis antibody painel
- EMG abnormalities but NCS usually ok
- Muscle biopsy
Describe pathology of polymyositis
Polymyositis pathology
- C8+ mediated
- Inflammation around normal muscle fibers
- Scattered necrosis, degeneration, regeneration
- Internal nuclei
- Variability of fiber size but seldom any hypertrophy
- Multifocal: biopsy weak but not wasted
Describe treatment of polymyositis
Polymyositis treatment
- Corticosteroids: prednisone or IV solumedrol
- Azathioprine
- Methotrexate
- iVIG
- Rituximab
(take time to be effective)
Describe dermatomyositis
Dermatomyositis
- Proximal weakness, dysphagia
- Female more than male
- Children and adults
- Skin manifestations: sun-exposed erythema, heliotrope rash, eczema on extensor surface of joints, hands, knees, elbows
- Other manifestations: ILD (50% anti-Jo-1 positive), malignancy, esophageal disease, vasculopathy in GI tract (kids), myocarditis, calcinosis
____ means patient has dermatomyositis
Gottron’s sign means patient has dermatomyositis
(also has extensor surface eczema and rash, heliotrope rash)
Dermatomyositis is associated with ____
Dermatomyositis is associated with malignancy
(muscle disease predates oncological manifestations)
Describe pathology of dermatomyositis
Dermatomyositis pathology
- Humorally mediated (CD4+): membrane attack complex at normal appearing capillaries
- Perivascular inflammation
- Perifascicular atrophy: may be more apparent on ATPase then H&E stain
(complement deposition towards the edge of muscle -> capillaries infiltrated -> not oxygenated)
____ is indicative of dermatomyositis
Perifascicular atrophy is indicative of dermatomyositis
Describe treatment for dermatomyositis
Dermatomyositis treatment
- Corticosteroids
- Azathioprine
- Methotrexate
- IVIG
- Rituximab
Describe malignancy in dermatomyositis
Dermatomyositis malignancy
- Cancer risk not increased in children
- Need malignancy evaluation and yearly screening for at least 2 years
- Ovarian cancer is most common in dermatomyositis
- Associated malignancy usually detected within 2 years of onset of symptoms but ovarian cancer out to 5 years
Describe inclusion body myositis
Inclusion body myositis
- Male predominance
- Most common male inflammatory process over age 50
- Distal weakness
- Asymmetry
- Quadriceps, wrist flexors, finger flexors
- Years for progression
Inclusion body myositis is characterized by ____ weakness and ____
Inclusion body myositis is characterized by distal weakness and asymmetry
Describe labs in inclusion body myositis
Inclusion body myositis labs
- CK mildly elevated
- NCS may show subclinical sensory neuropathy
- Anti-CNIA antibody: sensitivity of 33%
Describe pathology of inclusion body myositis
Inclusion body myositis pathology
- Rimmed vacuoles: seen on H&E but sometimes more apparent on Gomori trichrome
- Vacuoles contain beta-amyloid
- Light microscopy usually good enough for diagnosis
____ are indicative of inclusion body myositis
Rimmed vacuoles are indicative of inclusion body myositis
____ do not work in treatment of inclusion body myositis while ____ may
Steroids do not work in treatment of inclusion body myositis while IVIG may
Describe necrotizing myopathy
Necrotizing myopathy
- Little to no inflammation
- Lots of degeneration
- High CKs
- Relatively acute - 2/3 are from statin use due to antibody against HMG-CoA reductase
- Signal reduction particle
- Paraneoplastic
Describe HMG CoA reductase necrotizing myositis
HMG CoA reductase necrotizing myositis (statin associated necrotizing autoimmune myopathy)
- Mostly statin induced
- Antibodies to proteins
- Necrotizing myopathy on biopsy and EMG
- Responds to immunotherapy
- Residual weakness, may relapse with taper of immune modulating medications
Describe signal recognition particle myopathy
Signal recognition particle myopathy
- Immune-mediated necrotizing myopathy with myositis-specific autoantibody
- More common in African Americans and women
- CK very high, ANA and ESR often normal
- Necrosis and regeneration is predominant finding on muscle biopsy - minimal to no inflammation
- Dysphagia, Raynaud, myalgias common
- Responds to immunotherapy
Summarize the inflammatory myopathies
