MSK soft tissue pathology Flashcards by Robyn Baxter

What are the indications of muscle disease?

Raised creatinine kinase
Muscle weakness
Muscle atrophy
Fasciculation

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Describe the patterns of serum creatinine kinase level with respect to pathology

Raised 200x - muscular dystrophy
Raised 20x - inflammatory myopathy
Decreased 2x - neurogenic

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How can we categorise the two types of muscle pathology?

Muscle disease

Neurogenic disease causing muscle pathology

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List the different categories of myopathy

Muscular dystrophy
Inflammatory myopathy
Congenital 
Secondary
Metabolic

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Which age group presents with duchenne’s muscular dystrophy?

2-4 year olds

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How is duchenne’s muscular dystrophy inherited?

X-linked (so only males)

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What is the average life expectancy for someone with duchenne’s?

20 years old

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How does duchenne’s muscular dystrophy present?

Proximal muscle weakness
Pseudohypertrophied calf muscles
Gower’s sign

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How will creatinine kinase be affected in duchenne’s?

Grossly raised

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What gene is affected in DMD? What does this result in?

Dystrophin

Poor cytoskeleton anchorage to the basement membrane and thus muscle tearing

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How does DMD appear histologically?

Necrosis & regeneration
Chronic inflammation & fibrosis
Hypertrophy

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What is becker’s muscular dystrophy?

A less severe variant of DMD

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When does becker’s muscular dystrophy (BMD) present?

Later than DMD

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How fast does BMD progress?

Slowly

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What gene is affected in BMD?

Dystrophin (less severe mutation than DMD)

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What are the two types of myotonic dystrophy? How can they be clinically differentiated?

DM1 - distal muscles affected

DM2 - proximal muscles affected

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How does myotonic dystrophy present?

Muscle weakness
Myotonia (inability to relax muscle)
Extra-muscular features

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What are the extra muscular features of myotonic dystrophy?

Cataracts
Frontal baldness (males only)
Cardiomyopathy
Lowered intelligence

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How is myotonic dystrophy inherited? Which chromosome does it affect?

Autosomal dominant

C19 & C3

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Describe the natural history of myotonic dystrophy

Young patients - face and distal limbs affected

Older patients - respiratory muscles affected

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How does myotonic dystrophy present histologically?

Type 1 (red) muscle cell atrophy
Central nuclei
Necrosis
Fatty replacement

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What are the three main types of inflammatory myopathies?

Infective
Polymyositis
Dermatomyositis

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What is polymyositis?

A chronic inflammatory disease of the muscles

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How does polymyositis present?

Progressive muscle weakness
Progressive pain
Tenderness

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Describe the immunological component of polymyositis

Cell mediated immune response (lymphocytic and CD8 T cells) to muscle

How does polymyositis present histologically?

Segmental fibre necrosis

What is dermatomyositis?

Polymyositis plus skin changes

What is dermatomyositis associated with?

Malignancy!!

Describe the immunological component of dermatomyositis

Immune complex deposition in muscle capillaries (CD4 T cells and B cells)

What are neurogenic disorders of the muscle?

Nerve damage resulting in disorders of the muscle following re-innervation

List the categories of neurogenic muscle disorders

Motor neurone disease Spinal muscular atrophy Peripheral neuropathy Misc. spinal disorders

How do the muscle fibres appear histologically with respect to neurogenic muscle disorders in adults and children respectively?

Adults - small and angulated Children - small and round Fibre type grouping and atrophy

What is motor neurone disease?

Progressive degeneration of anterior horn cells

How does motor neurone disease present (generally)?

Muscle atrophy (due to denervation) Fasciculation Weakness

How is spinal muscle atrophy inherited? Which chromosome is affected?

Recessive | Chromosome 5

What is spinal muscle atrophy?

Degeneration of the anterior horn cells within the spinal cord causing denervation of muscle

What is myasthenia gravis?

An autoimmune condition against post synaptic acetylcholine receptors

How does myasthenia gravis present?

Muscle weakness Proptosis Fatigue Dysphagia

Who gets myasthenia gravis?

Women | 20-40 y/o

What is associated with myasthenia gravis?

Thymoma OR | Thymic hyperplasia

How can myasthenia gravis be treated?

Anti-cholinesterase drugs

What is rhabdomyolysis?

Skeletal muscle breakdown

What biochemical changes does rhabdomyolysis cause?

Raised myoglobin (coca cola urine) Hyperkalaemia Muscle necrosis

What complications can arise from rhabdomyolysis?

Acute kidney injury --> hypovolaemia Metabolic acidosis Disseminated intravascular coagulation

Are connective tissue diseases more common in males or females?

Females

How can connective tissue diseases be treated?

Anti-inflammatory drugs

What is systemic lupus erythmatosus?

Multi-system autoimmune condition

Which antibodies are positive in SLE?

ANA (anti nuclear antibodies)

Is SLE genetic?

It can play a part in inheritance

Which two drugs can cause SLE?

Hydralazine (anti-hypertensive) | Pracainamide (anti-arrhythmic)

What are the dermatological manifestations of SLE?

Malar butterfly rash UV hypersensitivity Discoid lupus erythematosis

How does SLE affect the joints?

Arthralgia

How does SLE affect the kidneys?

Glomerulonephritis

How does SLE affect the nervous system?

Psychiatric problems | Focal neurological

How does SLE affect the CVS?

Pericarditis Myocarditis Necrotising vasculitis

Can SLE present with lymphadenopathy?

Yes

How does SLE affect the lungs?

Pleuritis | Pleural effusion

How does SLE affect the haematological system?

Anaemia Leucopenia (low white cells) Thrombophilia (inc. clotting risk)

What two types of hypersensitivity are at play with regard to SLE?

Visceral - immune complex mediated (type III) | Haematological - type II

What is polyarteritis nodosa?

Inflammation and necrosis of small to medium arteries

Which organs are commonly affected by polyarteritis nodosa?

Kidneys Heart Liver GI tract

How might polyarteritis nodosa present?

``` Secondary hypertension (from kidneys) Haematuria Abdominal pain Melaena Diarrhoea Mononeuritis multiplex Rash Cough Dysphonea ```

What can be found on biopsy of polyarteritis nodosa?

Fibrinoid necrosis

What antibody is positive in polyarteritis nodosa?

pANCA

Who gets polymyalgia rheumatica?

Old people

How does polymyalgia rheumatica present?

Pain and stiffness in shoulder and pelvic girdle | NO muscle weakness

How is polymyalgia rheumatica treated?

Corticosteroids

What is temporal arteritis?

Vasculitic inflammation of the cranial vessels

What is the risk with temporal arteritis?

Blindness

How is temporal arteritis investigated?

Raised inflammatory markers | Temporal artery biopsy (skip lesions)

What is scleroderma?

Excessive collagen deposition (fibrosis) of organs/tissues

How does scleroderma affect the skin?

Tight immobile skin | Reduced movement

How does scleroderma affect the GI tract?

Fibrosis of muscles (dysphagia, etc)

How does scleroderma affect the CVS?

Pericarditis | Myocardial fibrosis --> HF/arrhythmias

How does scleroderma affect the lungs?

Interstitial fibrosis | Cor pulmonale

How does scleroderma affect the kidneys?

Attacks blood supply --> secondary hypertension --> CKD

How does scleroderma affect the MSK?

Polyarteritis | Myositis

What is the mnemonic used to remember the symptoms of scleroderma?

``` C alcinosis R aynaud's E sophageal dysphagia S clerodactyly T elangectasia ```

MSK soft tissue pathology Flashcards

(78 cards)