Antiphospholipid/ dermatomyositis/ polymyositis

Question 1

What is antiphospholipid syndrome

Answer 1

association of antiphospholipid antibodies- where the blood becomes more prone to clotting .

Question 2

Epidemiology of APS

Answer 2

• Associated with SLE in 20-30% of cases
• Often occurs as a primary disease (no underlying autoimmune disease)
• More common in females than males
• APS has been reported to have a prevalence of between 1.0% and 5.6% in normal healthy populations and may increase with age.

Question 3

Pathophysiology OF APS

Answer 3

• antiphospholipid antibodies (aPL) play a role in thrombosis by binding to phospholipid on the surface of cells such as endothelial cells, platelets and monocytes
• Once bound, it alters the functioning of those cells leading to thrombosis and/or miscarriage.
• Thrombotic tendency affects cerebral, renal and other vessels

Question 4

Antiphospholipid antibodies (aPL) cause CLOTs, what are clots

Answer 4

• Coagulation defect
• Livedo reticularis - lace-like purplish discolouration of skin
• Obstetric issues i.e. miscarriage
• Thrombocytopenia (low platelets)

Question 5

Clinical manifestations OF APS

Answer 5

• Thrombosis
• Miscarriage
• Livedo-reticularis
• Thrombocytopenia
• Ischaemic stroke, TIA, MI - arteries
• Deep vein thrombosis, Budd-chiari syndrome - veins
• Valvular heart disease, migraines, epilepsy

Question 6

Investigations of aps

Answer 6

• Anticardiolipin test:
  
  • Detects IgG or IgM antibodies that bind the negatively charged phospholipid - cardiolipin
• Lupus anticoagulant test:
  
  • Detects changes in the ability of the blood to clot
• Anti-B2-glycoprotein I test:
  
  • Detects antibodies that bind B2-glycoprotein I, a molecule that interacts closely with phospholipids
• A persistently positive test (positive on at least two occasions more than 12 weeks apart) in one or more of these tests, along with clinical features is needed to diagnose APS

Question 7

Management of aps

Answer 7

• Long term warfarin to minimise thrombosis
• Pregnant women:
  
  • Oral aspirin and SC heparin early on in pregnancy
  • Reduces chance of miscarriage but pre-eclampsia and poor fetal growth remain common
• Prophylaxis:
  
  • Aspirin or Clopidogrel for people with aPL, especially those with a high IgG aPL (antiphospholipid antibody)

Question 8

What is polymyositis and dermatomyositis

Answer 8

Polymyositis and dermatomyositis are autoimmune disorders where there is inflammation in the muscles (myositis)

Question 9

Polymyositis

Answer 9

condition of chronic inflammation of muscles.

Question 10

Dermatomyositis

Answer 10

connective tissue disorder where there is chronic inflammation of the skin and muscles.

Question 11

Key investigation for diagnosing myositis

Answer 11

creatine kinase blood test

Creatine kinase is an enzyme found inside muscle cells. Inflammation in the muscle cells (myositis) leads to the release of creatine kinase

Question 12

Creatine kinase levels

Answer 12

usually less than 300 U/L. In polymyositis and dermatomyositis, the result is usually over 1000, often in the multiples of thousands.

Question 13

Other causes of creatine kinase raised

Answer 13

Rhabdomyolysis
Acute kidney injury
Myocardial infarction
Statins
Strenuous exercise

Question 14

What can these diseases be caused by?

Answer 14

Underlying malignancy
makes them paraneoplastic syndromes. The most common associated cancers are:

Lung
Breast
Ovarian
Gastric

Question 15

Presentation of myosotis

Answer 15

Muscle pain, fatigue and weakness
Occurs bilaterally and typically affects the proximal muscles
Mostly affects the shoulder and pelvic girdle
Develops over weeks

Question 16

Dermatomyositis Skin Features

Answer 16

Gottron lesions (scaly erythematous patches) on the knuckles, elbows and knees
Photosensitive erythematous rash on the back, shoulders and neck
Purple rash on the face and eyelids
Periorbital oedema (swelling around the eyes)
Subcutaneous calcinosis (calcium deposits in the subcutaneous tissue)

Question 17

Autoantibodies in myositis

Answer 17

Anti-Jo-1 antibodies: polymyositis (but often present in dermatomyositis)
Anti-Mi-2 antibodies: dermatomyositis.
Anti-nuclear antibodies: dermatomyositis.

Question 18

Diagnosis is based on for myositis…?

Answer 18

Clinical presentation
Elevated creatine kinase
Autoantibodies
Electromyography (EMG)
Muscle biopsy can be used to establish a definitive diagnosis.

Question 19

Management of myositis

Answer 19

Management is guided by a rheumatologist. New cases should be assessed for possible underling cancer. They may require physiotherapy and occupational therapy to help with muscle strength and function.

Corticosteroids are the first line treatment of both conditions.

Other medical options where the response to steroids is inadequate:

Immunosuppressants (such as azathioprine)
IV immunoglobulins
Biological therapy (such as infliximab or etanercept)