Flashcards in Muscle pathology Deck (45)
What is the epimysium?
The fibrous sheath which surrounds the entire skeletal muscle
What is the endomysium?
The fibrous sheath which surrounds individual muscle fibres
What is the perimysium?
The fibrous sheath which surrounds groups of muscle fibres to create a fascicle
What are the indications for muscle biopsy?
Evidence of muscle disease - weakness, atrophy, raised CK
Presence of neuropathy
Presence of vascular disorder
What histological changes might be seen in muscular dystrophy?
Variability in size of muscle fibres
Increased central nuclei
What are muscular dystrophies?
A group of inherited diseases that cause progressive weakening of muscles
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
When does Duchenne Muscular Dystrophy typically present?
2-4 years old
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
What is myositis ossificans?
A condition where heterotopic ossification (bone forming outside the skeleton) occurs in muscles usually after an injury
What are polymyositis and dermatomyositis?
Idiopathic inflammatory myopathies
Which gender do polymyositis and dermatomyositis affect?
What is the peak age of incidence in polymyositis and dermatomyositis?
What are patients with polymyositis and dermatomyositis at increased risk of?
Malignancy, particularly dermatomyositis (15%)
Lung, breast, ovarian, stomach, colon and bladder
Which patients with polymyositis and dermatomyositis in particular are at risk of malignancy?
What cutaneous signs may be present in dermatomyositis?
Gottrons sign (fingers and knuckles)
What other organs may be involved in polymyositis and dermatomyositis?
Lungs: respiratory muscle weakness and interstitial lung disease, breathlessness, cough
What general systemic symptoms may be present in polymyositis and dermatomyositis?
What other diseases are polymyositis and dermatomyositis associated with?
What drugs are development of polymyositis and dermatomyositis associated with?
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
What blood tests should be done to investigate polymyositis and dermatomyositis?
Electrolytes, calcium, PTH, TSH to exclude other causes
What auto-antibodies may be present in polymyositis and dermatomyositis?
What investigations should be done to confirm polymyositis and dermatomyositis?
What would be seen on electromyography in polymyositis and dermatomyositis?
Abnormal motor potentials
Complex repetitive discharges
What would be seen in muscle biopsy in polymyositis and dermatomyositis?
Perivascular inflammation and muscle necrosis
What would be seen on MRI of polymyositis and dermatomyositis?
Muscle inflammation, oedema, fibrosis and calcification
What is the treatment for polymyositis and dermatomyositis?
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