Inflammatory Myopathies Flashcards
Dermatomyositis, polymyositis, and inclusion body myositis are all examples of ___
inflammatory myopathies
How common are inflammatory myopathies?
Uncommon, 1 in 100,000 annually
Are inflammatory myopathies suppurative?
Nonsuppurative inflammation
Inflammatory myopathies have what four characteristics?
- Presence of inflammatory cells
- Necrosis and phagocytosis of muscle fibers
- A mixture of regenerating and atrophic fibers
- Fibrosis
Which muscles commonly experience weakness with inflammatory myopathies?
Symmetrical proximal muscles (shoulders, hips, torso) (can eventually go distal)
How do inflammatory myopathy symptoms progress over time?
Gradually increasing symptoms over weeks or months
Progressive difficulties with activities of daily living (lifting object, climbing stairs, combing hair, holding head up)
Inflammatory myopathy lab results show increased ___
- serum muscle-derived enzymes
- ESR
- (maybe) C-reactive protein
Inflammatory myopathies are commonly comorbid with ___
other autoimmune conditions (antibodies tested to determine which)
How are inflammatory myopathies generally treated?
Autoimmune treatments:
- Corticosteroids
- Immunosuppressant drugs (DMARDs) or IV immunoglobulin
Which inflammatory myopathy has no effective therapy?
Inclusion body myositis
Does dermatomyositis more often affect children or adults?
Adults
Dermatomyositis is likely comorbid with ___
systemic sclerosis or other autoimmune disorders
A patient presents with a rash on their upper eyelids, face, trunk, and some other areas. It is known that this patient has systemic sclerosis, but now there is evidence of necrosis of skeletal muscle tissue and fiber atrophy.
What is the likely diagnosis?
Dermatomyositis
What is the etiology of dermatomyositis?
Autoimmune
With dermatomyositis, compliment mediated (humoral immunity) antibodies attack ___ of skeletal muscle
microvasculature
angiopathy, microvasculitis
With dermatomyositis, ___ attack microvasculature of skeletal muscle (angiopathy)
compliment mediated antibodies (humoral immunity)
Dermatomyositis involves ischemia of ___ which leads to ___
ischemia of individual muscle fibers which leads to necrosis of skeletal muscle tissue and fiber atrophy
Why might infarcts occur with dermatomyositits?
Due to involvement of large intramuscular arteries
Is dermatomyositis limited to skeletal muscle?
No, a similar process will affect other tissues and organs (ie. diaphragm)
What is the etiology of polymyositis?
Autoimmune
Polymyositis almost always begins after age ___
20
Which sex is predominantly affected by polymyositis?
Females
Does polymyositis involve a skin rash or microvasculopathy?
No
Does polymyositis involve angiopathy?
No
How are T cells related to polymyositis?
T cells directly attack muscle fibers
What is represented histologically in polymyositis?
- Macrophages in muscle tissue
- Necrosis
- Phagocytosis
- Regeneration
- Fibrosis
Does polymyositis progress systemically or locally?
Systemic progression
Polymyositis has similar muscle inflammation as that of which is seen in ___
HIV infection
What is the nature of degeneration associated with polymyositis?
Degeneration is scattered, and not always in the areas of inflammation
What is the most common inflammatory myopathy in geriatrics?
Inclusion body myositis
Inclusion body myositis most commonly presents at what age?
Over age 50
Which sex is predominantly affected by inclusion body myositis?
Males
Inclusion body myositis involves the presence of specific antigen on ___
sarcolemma
How are T cells related to inclusion body myositis?
What is this similar to?
T cells attack skeletal muscle fiber; similarly to polymyositis
What is found histologically in inclusion body myositis?
Basophilic granular inclusions in the cytoplasm or nuclei of involved muscle fibers and near vacuoles
Inclusion body myositis primarily involves which regions of the body?
Distal muscles: hands and feet
A 55-year-old male presents with atrophy of skeletal muscle tissue in their hands. Upon biopsy, the involved muscle fibers show basophilic granular inclusions containing intracellular B-amyloid plaque throughout the cytoplasm and nuclei.
What is the diagnosis?
Inclusion body myositis
What is found in the inclusions of muscles affected by inclusion body myositis?
- B-amyloid plaque
- Tau proteins and other proteins associated with Alzheimer present
- Parkin (associated with Parkinson disease) and the prion precursor protein have also been found
What are the ESR and CRP levels in someone with inclusion body myositis?
Elevated
How does inclusion body myositis respond to therapy?
Poorly
