Flashcards in Muscle pathology Deck (45)
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1
What is the epimysium?
The fibrous sheath which surrounds the entire skeletal muscle
2
What is the endomysium?
The fibrous sheath which surrounds individual muscle fibres
3
What is the perimysium?
The fibrous sheath which surrounds groups of muscle fibres to create a fascicle
4
What are the indications for muscle biopsy?
Evidence of muscle disease - weakness, atrophy, raised CK
Presence of neuropathy
Presence of vascular disorder
5
What histological changes might be seen in muscular dystrophy?
Variability in size of muscle fibres
Endomysial fibrosis
Fatty infiltration
Increased central nuclei
Segmental necrosis
6
What are muscular dystrophies?
A group of inherited diseases that cause progressive weakening of muscles
7
What is the pathophysiology of muscular dystrophies?
There is destruction of single muscle fibres in the muscles, which are then regenerated
This causes fibrosis of the muscles
8
When does Duchenne Muscular Dystrophy typically present?
2-4 years old
9
What is the pathophysiology of Duchenne muscular dystrophy?
There is a mutation of the dystrophin gene on the long arm of chromosome X
Actin fibres don't adhere properly to the basement membrane, leaving fibres liable to tearing
There is uncontrolled Ca2+ entry into cells
10
What is myositis ossificans?
A condition where heterotopic ossification (bone forming outside the skeleton) occurs in muscles usually after an injury
11
What are polymyositis and dermatomyositis?
Idiopathic inflammatory myopathies
12
Which gender do polymyositis and dermatomyositis affect?
Female:male 2:1
13
What is the peak age of incidence in polymyositis and dermatomyositis?
40-50
14
What are patients with polymyositis and dermatomyositis at increased risk of?
Malignancy, particularly dermatomyositis (15%)
Lung, breast, ovarian, stomach, colon and bladder
15
Which patients with polymyositis and dermatomyositis in particular are at risk of malignancy?
Men >45
16
What cutaneous signs may be present in dermatomyositis?
Gottrons sign (fingers and knuckles)
Heliotrope rash
Shawl sign
17
What other organs may be involved in polymyositis and dermatomyositis?
Lungs: respiratory muscle weakness and interstitial lung disease, breathlessness, cough
Heart: myocarditis
Oesophagus: dysphagia
18
What general systemic symptoms may be present in polymyositis and dermatomyositis?
Fever
Weight loss
Raynaud's
Non-erosive polyarthritis
19
What other diseases are polymyositis and dermatomyositis associated with?
Diabetes mellitus
Thyroid disease
20
What drugs are development of polymyositis and dermatomyositis associated with?
Steroids
Statins
21
What tests on examination can be done to investigate polymyositis and dermatomyositis?
Confrontational testing - direct testing of power
Isotonic testing - 30 second sit to stand test
22
What blood tests should be done to investigate polymyositis and dermatomyositis?
Creatine kinase
Inflammatory markers
Electrolytes, calcium, PTH, TSH to exclude other causes
23
What auto-antibodies may be present in polymyositis and dermatomyositis?
ANA
Anti-Jo-1
24
What investigations should be done to confirm polymyositis and dermatomyositis?
Electromyography (EMG)
Muscle biopsy
MRI
25
What would be seen on electromyography in polymyositis and dermatomyositis?
Increased fibrillations
Abnormal motor potentials
Complex repetitive discharges
26
What would be seen in muscle biopsy in polymyositis and dermatomyositis?
Perivascular inflammation and muscle necrosis
27
What would be seen on MRI of polymyositis and dermatomyositis?
Muscle inflammation, oedema, fibrosis and calcification
28
What is the treatment for polymyositis and dermatomyositis?
Glucocorticoids
Azathioprine
Methotrexate
Ciclosporin
IV immunoglobulin
29
What is inclusion body myositis?
An inflammatory muscle disease, characterized by slowly progressive weakness and wasting of mostly distal, but some proximal muscles, most apparent in the muscles of the arms and legs
30
