Flashcards in Pathology Deck (76)
What are some indications for a muscle biopsy?
Evidence of muscle disease:
- Symptoms (Atrophy, Fasciculation)
- Increased CK
Presence of neuropathy (Do nerve biopsy too)
Presence of vasculitis
In what disorders is CK high? How do we class high CK?
200-300 times normal
In what disorders is CK intermediate? How do we class intermediate CK?
20-30 times normal
In what disorders is CK relatively low? How do we class relatively low CK?
2-5 times normal
What can be seen in muscle dystrophy on biopsy?
Variable fibre size
Fatty infiltrate + replacement:
- Clear spaces on histology
Increased central nuceli
Why is segmented necrosis seen in muscle dystophy biopsies?
Parts of individual muscle fibres controlled by different nuclei
What are ring fibres?
Striated anulets on histology
What are some general pathological features seen in all muscular dystrophies?
Destruction of single fibres
Regeneration of fibres
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
What are pathogenic features of DMD?
Anchorage of actin to basement membrane
Uncontrolled calcium entry into cells
What investigations could be requested in DMD and what would the expected results be?
Serum creatinine phosphokinase:
- Fibre necrosis and phagocytosis
- Chronic inflammation and fibrosis
What is Becker Muscular Dystrophy and how does it differ from DMD?
Essentially a variant of DMD but:
- Later onset
- Slower progress
At what age to DMD patients tend to die?
What tends to cause death in DMD?
How is BMD inherited?
What are the two most common types of myotonic dystrophy?
How is myotonic dystrophy inherited?
- Ch19 (DM1)
- Ch3 (DM2)
What muscles are affected in the following stages of myotonic dystrophy:
1. Face and distal limbs
2. Respiratory muscles
What are the histological features of myotonic dystrophy?
Atrophy of Type i skeletal muscle fibres
What is the immunopathogenesis of polymyositis?
Cell-mediated immune response to muscle antigens:
- CD8+ T cells in endomysium
What type of fibre necrosis is seen in polymyositis?
What are the clinical signs of polymyositis?
Progressive proximal muscle weakness
A patient present with difficult climbing the stairs and brushing her hair. You notice a purple heliotrope rash around her eyes.
Where are immune complexes and complement deposited in dermatomyositis?
Within and around muscle capillaries
What sort of fibre injury is seen in dermatomyositis?
Why lymphocytes infiltrate the muscle fibres in dermatomyositis?
CD4+ T cells
What is the general histological appearance of a muscle biopsy in neurogenic muscle disorders?
Small, angulated fibres (adults)
Small, round fibres (kids)
Fibre type grouping
What causes motor neurone disease?
Progressive degeneration of anterior horn cells