Flashcards in Pathology Deck (76)
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1
What are some indications for a muscle biopsy?
Evidence of muscle disease:
- Weakness
- Symptoms (Atrophy, Fasciculation)
- Increased CK
Presence of neuropathy (Do nerve biopsy too)
Presence of vasculitis
2
In what disorders is CK high? How do we class high CK?
Dystrophies
200-300 times normal
3
In what disorders is CK intermediate? How do we class intermediate CK?
Inflammatory myopathies
20-30 times normal
4
In what disorders is CK relatively low? How do we class relatively low CK?
Neurogenic disorders
2-5 times normal
5
What can be seen in muscle dystrophy on biopsy?
Variable fibre size
Endomysial fibrosis
Fatty infiltrate + replacement:
- Clear spaces on histology
Myocyte hypertrophy
Fibre splitting
Increased central nuceli
6
Why is segmented necrosis seen in muscle dystophy biopsies?
Parts of individual muscle fibres controlled by different nuclei
7
What are ring fibres?
Striated anulets on histology
8
What are some general pathological features seen in all muscular dystrophies?
Destruction of single fibres
Prolonged
Regeneration of fibres
Fibrosis
9
A 3 year old patient is brought to you by his father. He is concerned about the fact that his son has been walking on his tiptoes a lot and falls a lot when he tries to run. On examination, the boy stands up by walking his hands towards his feet and has swollen 'woody' calves. What is the diagnosis and genetic cause of this disease?
Duchenne Muscular Dystrophy:
- Dystrophin gene mutation
- X linked recessive
10
What are pathogenic features of DMD?
Anchorage of actin to basement membrane
Uncontrolled calcium entry into cells
11
What investigations could be requested in DMD and what would the expected results be?
Serum creatinine phosphokinase:
- Raised
Muscle biopsy:
- Fibre necrosis and phagocytosis
- Regeneration
- Chronic inflammation and fibrosis
- Hypertrophy
12
What is Becker Muscular Dystrophy and how does it differ from DMD?
Essentially a variant of DMD but:
- Later onset
- Slower progress
13
At what age to DMD patients tend to die?
20
14
What tends to cause death in DMD?
Dilated cardiomyopathy
15
How is BMD inherited?
X-Linked recessive
16
'Hatchet-like' face?
Myotonic dystrophy
17
What are the two most common types of myotonic dystrophy?
DM1
DM2
18
How is myotonic dystrophy inherited?
Autosomal dominant:
- Ch19 (DM1)
- Ch3 (DM2)
19
What muscles are affected in the following stages of myotonic dystrophy:
1. Adolescent
2. Late
1. Face and distal limbs
2. Respiratory muscles
20
What are the histological features of myotonic dystrophy?
Atrophy of Type i skeletal muscle fibres
Central nuclei
Fibre necrosis
Fibrofatty replacement
21
What is the immunopathogenesis of polymyositis?
Cell-mediated immune response to muscle antigens:
- CD8+ T cells in endomysium
22
What type of fibre necrosis is seen in polymyositis?
Segmental
23
What are the clinical signs of polymyositis?
Progressive proximal muscle weakness
Pain
Tenderness
24
A patient present with difficult climbing the stairs and brushing her hair. You notice a purple heliotrope rash around her eyes.
Dermatomyositis
25
Where are immune complexes and complement deposited in dermatomyositis?
Within and around muscle capillaries
26
What sort of fibre injury is seen in dermatomyositis?
Perifascicular
27
Why lymphocytes infiltrate the muscle fibres in dermatomyositis?
B cells
CD4+ T cells
28
What is the general histological appearance of a muscle biopsy in neurogenic muscle disorders?
Small, angulated fibres (adults)
Small, round fibres (kids)
Target fibres
Fibre type grouping
Grouped atrophy
29
What causes motor neurone disease?
Progressive degeneration of anterior horn cells
30
