Cortex rheumatology - Inflammatory arthropathies 4

Question 1

What is gout ?

Answer 1

A crystal arthropathy caused by deposition of urate crystals within a joint, usually due to high serum uric acid levels (hyperuricaemia)

Question 2

What is the typical presentation of gout ?

Answer 2

• Uric acid crystals precipitate in joints.
• The classic joint affected is the first metatarsalphalangeal (MTP) (big toe), ankle and knee the other most commonly affected joints.
• Presents with an intensely painful red, hot swollen joint
• Gouty tophi are painless white accumulations of uric acid which can occur in the soft tissues and occasionally erupt through the skin

Question 3

What sign is shown here and what condition is it associated with ?

Answer 3

Gouty tophi - painless white accumulations of uric acid which can occur in the soft tissues and occasionally erupt through the skin.

Question 4

How is gout diagnosed ?

Answer 4

Diagnosed by analysing a sample of synovial fluid with polarised microscopy

1st line - arthrocentesis with synovial fluid analysis

Uric acid crystals are needle shaped and display negative birefringence (change from yellow to blue when lined across the direction of polarization).

Also check inflam markers + X-ray (same with pseudogout)

Question 5

Describe the treatment of gout

Answer 5

Acute gout:

• 1st line: non-steroidal anti-inflammatory drug (NSAID)
• 2rd line: colchicine
• 3nd line: corticosteroid

Recurrent gout - not started until acute attack subsided:

• 1st line - xanthine oxidase inhibitor - allopurinol

Question 6

What is pseudogout?

Answer 6

Is another crystal arthropathy causing an acute arthritis but, in contrast to gout, it is caused by calcium pyrophosphate crystals.

Question 7

How is pseudogout diagnosed ?

Answer 7

Diagnosed by:

Arthrocentesis with synovial fluid analysis - showing Positively birefringent crystals of calcium pyrophosphate

Question 8

Who does pseudogout typically occur in ?

Answer 8

CPPD typically occurs in older patients but can occur in younger patients with associated metabolic conditions, such as hyperparathyroidism, hypothyroidism, renal osteodystrophy, haemochromatosis and Wilson’s disease.

Question 9

What are the key features of pseudogout ?

Answer 9

Key factors:

• presence of risk factors
• painful and tender joints
• osteoarthritis-like involvement of joints (wrists, shoulders)
• sudden worsening of osteoarthritis

Other diagnostic factors:

• red and swollen joints
• joint effusion and fluctuance
• fever and malaise

Question 10

What are the key differences between gout and pseudogout ?

Answer 10

• Gout - caused by uric acid crystals and has negative brifringement
• Pseudogout - caused by calcium pyrophosphate crystals and has slightly positive bifringement
• In pseudogout - x-ray: chondrocalcinosis

in the knee this can be seen as linear calcifications of the meniscus and articular cartilage

Question 11

What is the treatment of pesudogout ?

Answer 11

• 1st line = NSAIDs
• 2nd line = Corticosteroids (systemic and intra‐articular)
• and occasionally colchicine

Question 12

What is polymyalgia rheumatica ?

Answer 12

• Common chronic inflammatory condition affecting mainly elderly people (>50)
• Characterized by proximal myalgia of the hip and shoulder girdles with accompanying morning stiffness that lasts for more than 1 hour.

Question 13

What condition is strongly associated with polymyalgia rheumatica ?

Answer 13

GCA - giant cell arteritis

Question 14

How is a diagnosis of PMR reached and what is its treatment?

(hint diagnosis and treatment tie in with each other)

Answer 14

• No specific test but almost always CRP and PV/ESR are raised (hence inflammatory condition)
• Patients respond to treatment very quickly (basically fine the next day)
• Treatment = prednisiolone, dose is gradually reduced over the course of around 18 months (should resolve by then)

Question 15

What is giant cell arteritis (GCA) ?

Answer 15

A granulomatous vasculitis of large and medium-sized arteries.

Question 16

Describe the histopathology of GCA

Answer 16

Marked by transmural inflammation of the intima, media, and adventitia of affected arteries, as well as patchy infiltration by lymphocytes, macrophages, and multinucleated giant cells.

Vessel wall thickening can result in arterial luminal narrowing, resulting in subsequent distal ischemia.

Question 17

What are the common signs/symptoms of GCA?

Answer 17

• Visual disturbances
• Headache
• Jaw claudication
• Scalp tenderness

Question 18

Who should GCA always be considered in ?

Answer 18

Patients > 50 presenting with a new onset headache with elevated CRP or ESR/PV

Question 19

How is GCA diagnosed ?

Answer 19

Inflammatory markers are almost always raised.

The most definitive test is a temporal artery biopsy. (has 100% specificity but 15-40% sensitivity)

Question 20

What must be done if someone presents with symptoms of GCA + visual symptoms ?

Answer 20

Fundoscopy + Immediate Ophthalmology referral!

Regardless of visual symptoms or not always do fundoscopy will see ischaemic optic neuropathy

Question 21

How is GCA treated ?

Answer 21

Treated with corticosteroids as soon as diagnosis suspected (before even biopsy taken)

1st line - prednisolone, dose is gradually tapered over around 2 years (most will resolve during this)

Question 22

What is polymyositis ?

Answer 22

An idiopathic inflammatory myopathy that causes symmetrical, proximal muscle weakness.

Question 23

What is dermatomyositis ?

Answer 23

An inflammatory disorder like polymyositis which causes symmetrical, proximal muscle weakness but it also has characteristic skin lesions

Question 24

What age group does polymyositis and dermatomyositis most commonly affect ?

Answer 24

Usually above 20, esp aged 45-60

Question 25

Describe the pathogenesis of polymyositis (think this is the same for dermatomyositis also)

Answer 25

• It is a T-cell–mediated cytotoxic process directed against unidentified muscle antigens
• CD8 T cells, along with macrophages, initially surround healthy nonnecrotic muscle fibers and eventually invade and destroy them.

Question 26

Describe the typical presentation of polymyositis (remember this is the same for dermatomyositis but just has the cutaneous manifestations)

Answer 26

• Usually present with symmetrical, proximal muscle weakness in the upper and lower extremities
• Commonly noticed as difficulty with particular activities e.g. climbing stairs
• Some have myalgia (muscle pain)

Question 27

What are some of the complications that can occur due to polymyositis and dermatomyositis ?

Answer 27

• Dysphagia secondary to oropharyngeal and esophageal involvement
• Interstitial lung disease

Question 28

What can dermatomyositis be caused by and therefore what should be done ?

Answer 28

• May be idiopathic or associated with connective tissue disorders or underlying malignancy (typically ovarian, breast and lung cancer, found in 20-25% - more if patient older).
• Screening for an underlying malignancy is usually performed following a diagnosis of dermatomyositis