Pathology Flashcards
colour of type 1 skeletal muscle fibres
red
colour of type 2 skeletal muscle fibres
white
features of type 1 skeletal muscle fibres
large mitochondria and high myoglobin
resistant to fatigue due to ability to regenerate ATP
features of type 2 skeletal muscle fibres
small mitochondria and large motor end plates
fatigue rapidly, good for short bursts of energy
CK levels in dystrophies
high
200-300x normal
CK levels in inflammatory myopathies
intermediate 20-30x normal
CK levels in neurogenic disorders
low 2-5x normal
features of DMD
proximal weakness
pseudoypertrophy of the calves
Mutation in DMD
dystrophin gene on long arm X chromosome
Effect of mutation in DMD
alterations in anchorage of actin cytoskeleton to basement membrane
uncontrolled calcium entry into cells
Histology in DMD
muscle fibre necrosis and phagocytosis
chronic inflammation and fibrosis
Which is worse - DMD or Becker MD?
DMD
Where is the mutation in BMD
dystrophin gene
Most common type of muscular dystrophy
myotonic dystrophy
Inheritance of myotonic dystrophy
autosomal dominant
Ch19/Ch3
Histology of myotonic dystrophy
atrophy of type 1 fibres central nuclei ring fibres fibre necrosis fibrofatty replacement
Pathophysiology of polymyositis
cell-mediated immune response to muscle antigens
Histology of polymyositis
endomysial lymphocytic infiltrate, invasion of muscle by CD8+ T lymphocytes
What is dermatomyositis?
skin changes + polymyositis
What is the association of malignancy with dermatomyositis
10%
Histology of dermatomyositis
B lymphocytes and CD4+ T cells
What is motor neurone disease
progressive degeneration of the anterior horn cells
characterised by denervation atrophy, fasciculation and weakness
What is spinal muscular atrophy
degeneration of the anterior horn cells in the spinal cord
How is spinal muscular atrophy inherited?
autosomal recessive
Ch5
What kind of disease is myasthenia gravis
autoimmune
What are the characteristics of myasthenia gravis
weakness
proptosis
fatigue
dysphagia`
what are the antibodies in myasthenia gravis
anti-nicotinic ACh receptor antibodies
what do 25% of myasthenia gravis patients also have?
thymoma
what is rhabdomyolysis?
breakdown of skeletal muscle
what is polyarteritis nodosa
inflammation and fibrinoid necrosis of small/medium arteries
how is polyarteritis nodosa diagnosed
biopsy shows fibrinoid necrosis of vessels
serum pANCA
What does polymyalgia rheumatica respond well to
corticosteroids
what is temporal arteritis also known as
giant cell arteritis
what are patients with GCA at risk of
blindness
Complaint in GCA
headache and scalp tenderness
diagnosis of GCA
temporal artery biopsy
ESR is raised
what is scleroderma?
excessive fibrosis of organs and tissues due to excessive collagen production
CREST syndrome
calcinosiss raynauds esophageal dysfunction sclerodactyly telangiectasia