Buku Medicine

General principles

General principles 

Autoimmune connective tissue diseases comprise a spectrum of conditions that can affect multiple organs and tissues. They can be associated with autoantibodies that are associated with clinical phenotypes but there is also overlap between many of these conditions. 

Connective tissue diseases include: 

  • Systemic lupus erythematosus (SLE) 
  • Sjögren’s syndrome 
  • Systemic sclerosis 
  • Autoimmune myositis (dermatomyositis and polymyositis) 
  • Mixed connective tissue disease (MCTD) 
  • Relapsing polychondritis (RP) 

Vasculitis covers a range of disparate conditions. They are often divided by the size of vessels affected as this influences the clinical features and treatment. 

Antiphospholipid syndrome

Quick tip; Consider in patients with a history of both arterial AND venous thrombosis, especially if also a history of pregnancy losses

  • Increased risk of thrombosis in any vascular bed (arterial, venous, capillary). 
  • Can be associated with CTD, especially SLE. 
  • Consider in unprovoked DVT, strokes in young people, recurrent pregnancy losses. 
  • 50% who have APLS-associated thrombus will have a recurrence without treatment. 
  • Often identified by screening patients with CTD and those with recurrent pregnancy losses or unprovoked thrombosis (arterial or venous).  

 

History 

  • Consider in cases of unprovoked blood clots or those in an unusual site e.g splenic vein thrombosis. To fulfil diagnostic criteria must have one of the following and a positive laboratory test for APLS: 
    • 1 or more thrombus (arterial, venous or small vessel) in any tissue/organ. 
    • 1 or more foetal deaths after 10 weeks gestation of morphologically normal foetus. 
    • 1 one more premature births of a normal neonate before 34 weeks due to:  
      • Eclampsia/ severe pre-eclampsia 
      • Placental insufficiency/IUGR 
    • 3 or more unexplained consecutive miscarriages before 10 weeks gestation. 

Bloods 

  • In unexplained thrombosis or recurrent miscarriage discuss with haematology for alternative causes. Tests for anti-phospholipid syndrome include: 
    • Lupus anticoagulant (needs to be positive on two occasions at least 12 weeks apart)
    • Anticardiolipin antibody 
    • Anti B2 glycoprotein-1 antibody  

Myositis

Myositis 

  • Muscle inflammation has a range of causes including drugs, rhabdomyolysis and idiopathic inflammatory myopathies (dermatomyositis, polymyositis). 
  • Characterised by muscle pain and weakness. 
  • Usually identified in symptomatic patients following a screening test such as creatine kinase (CK). 
  • Autoimmune myositis can be paraneoplastic. 

 

History and examination 

  • History: 
    • Muscle weakness - can be of acute or insidious onset 
      • Autoimmune myositis is commonly symmetrical and proximal. 
    • Skin: heliotrope rash, Gottron’s papules, Gottron’s sign, shawl pattern. 
    • Worrying features - needs urgent review: 
      • Dyspnoea 
      • Dysphonia or dysphagia 
  • At presentation: 
    • FBC, ESR, U&E, bone, LFT (ALT can be raised due to muscle inflammation), CRP 
    • CK, AST, LDH 
    • TSH 
    • Urine dip 
  • In secondary care: 
    • Immunology: extended myositis screen - there are numerous auto-antigens associated with different presentations, complications and outcomes (e.g. high risk of malignancy in anti-HIF1a) 
    • Lung function testing 
    • ECG, CXR 
    • CT CAP to assess for malignancy and associated interstitial lung disease 
    • MRI of involved muscles 
    • Muscle biopsy 
    • EMG 

Differential - seek advice if raised CK of unknown cause, even if patient asymptomatic. The list of potential causes is long but includes: 

  • Drugs 
  • Inherited (metabolic myopathies and muscular dystrophies) 
  • Neuromuscular disorders  
  • Rhabdomyolysis 
  • Endocrine  
  • Infectious 

Referral 

  • Call rheumatology or admit out of hours if: 
  • Speech/swallow impairment 
  • Shortness of breath 
  • Rapidly progressive muscle weakness 

Other CTD syndromes

Undifferentiated CTD 

  • ANA positive with some clinical features of 1 or more systemic rheumatic disease but does not meet individual disease criteria. 
  • Accounts for 25% of referrals. 
  • Around a third will progress to fulfil diagnostic criteria for a specific CTD. 

 

Mixed CTD 

  • Overlap features of systemic sclerosis, systemic lupus erythematous and inflammatory myopathy. 
  • Unlikely without Raynaud’s phenomenon. 
  • Associated with high ANA tires and U1-RNP antibodies. 
  • Doesn’t usually involve severe renal disease or neurological disease. 
  • Associated with pulmonary hypertension and ILD. 

 

Overlap CTD 

  • Features of >1 of the following 6 conditions: SLE, systemic sclerosis, polymyositis, dermatomyositis, rheumatoid arthritis, Sjögren’s syndrome. 

 

Sjögrens syndrome

  • Characterised by Sicca symptoms (dry eyes and mouth). 
  • Can be associated with other rheumatic diseases or can be primary. 
  • Treatment is predominantly supportive. 
  • Associated with a 5-fold increased risk of developing non-Hodgkin lymphoma. 
  • Ro and La antibodies have implications on pre-pregnancy planning and obstetric monitoring and management (risk of neonatal heart block). 

History and examination 

  • History; 
    • Daily persistent dry eyes > 3 months 
    • Difficult to swallow without water 
    • Fatigue is common 
    • Associated with anti-Ro and anti-La antibodies 
    • Ask about B symptoms (fever, weight loss, night sweats, swollen lymph nodes) 
  • Examination; 
    • Parietal/ salivary gland swelling and lymphadenopathy - higher risk of lymphoma 
  • Bloods; 
    • At presentation; 
      • FBC, ESR, U&E, CRP, bone, LFT 
      • Immunology: ANA, ENA, immunoglobulins  
    • Secondary care; 
      • Schirmer’s test, salivary flow test, salivary ultrasound, labial (salivary lip ) biopsy 

SLE (lupus)

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Systemic sclerosis

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