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Systemic Lupus Erythematosus (SLE)

A multi-system inflammatory autoimmune disorder characterised by auto-antibodies
Most common presentations --> Arthalgia and rashes
Most serious --> Renal and brain


Epidemiology of SLE

1:9/M:F . Peak onset between 20-40yrs
Incidence varies between populations -- highest in african american women (1/250)


Pathogenesis of SLE

Auto-antibodies against nuclear antigens
Damage is either by direct binding of these autoantibodies to tissue or the formation of immune complexes --> activates the complement system causing neutrophilic infiltration + increased cytokines


Risk factors for SLE

Genetics -- 25% MZ concordance, 3% risk if 1st degree relative affected, Genes for HLA A1,B8 and DR3 + complement system are implicated
Female sex hormones -- premenopausal women most effected (also XXY men), HRT increases the risk of a flare
UV light and EBV are considered triggers for the disease or skin flare ups (UV light esspecially)


Cytokines in SLE

IL-10 and interferon-a are raised and their level tends to be related to level of SLE activity


Drug induced SLE

Hydralazine, Isoniazid, procainamide & Penicillamine can induce a mild form of SLE (no renal or CNS involvement)


Causes of tissue damage in SLE

Skin & kidneys --> Immune complex or IgG deposition and complement activation - may also be neutrophil/lymphocyte infiltration
Systemic vasculitis can occur and immune complex deposition can cause synovial inflammation and arthralgia


Clinical features of SLE

Vary greatly between patients -- most patients will have fatigue/malaise, arthralgia and skin problems -- fever is common during flares
Constitutional symptoms do not tend to correlate with disease activity or organ involvement
Organ involvement is rarer and more serious


Arthralgia in SLE

The most common feature (>90%) - similar presentation to RA with symmetrical small joint pain -- clinically normal but can be slight soft tissue swelling - joint deformity/erosion are rare


Muscle pain in SLE

Myalgia will be seen in 50% of patients but true myositis only in 5% -- is myositis is present there may be an overlap syndrome with myositis and SLE


Skin involvement in SLE

85% have some skin involvement -- butterfly erythema across the face is characteristic but vasculitic (urticara & purpura) lesions of the finger tips & nail folds can occur
Also: Livdeo reticularis, palmar/plantar rashes, changes in pigmentation and scarring alopecia


Lung involvement in SLE

50% of pts will have at some point in the disease -- most common --> Bilateral, recurrent pleurisy & exudate effusions
Shrinking lung syndrome, pulmonary fibrosis or intra- pulmonary haemorrhage are rare complications


Heart and CVS disease in SLE

Involved in 25% -- small effusive pericarditis or mild myocarditis (causing arrhythmia) are the most common. Aortic valve lesions and cardiomyopathy can also occur.
Vascular complications are more commonly seen if there is overlap with APS but there is a general increased MI/CVA risk in SLE


Renal involvement in SLE

Only in 30% of pts -- 1/3 of them will reach ESRF within 10yrs
Six classes of lupus nephritis (prognosis is best with types I,II and V) -- management is controlling oedema & HTN,


CNS involvement in SLE

Flucating symptoms are seen in up to 60% of pts -- mild depression and rarely more severe psychiatric symptoms occur
multiple mechanisms of cerebral damage and MRI findings are usually increased white matter signal --> migraine, epilepsy, ataxia, meningitis, CN lesions or polyneuropathy can occur


Eye involvement in SLE

Retinal vasculitis --> infarcts (cytoid bodies) --> appear as hard exudates and haemorrhages
Also: episcleritis, conjunctivitis or optic neuritis --> blindness is uncommon
Secondary Sjogren's occurs in 15% of cases


GI involvement in SLE

Mouth ulcers are common and may be a presenting feature
Usually initally painless but may become infected
Mesenteric vasculitis can cause bowel infarcts
Liver/pancreas involvement is uncommon


Blood investigations for SLE

FBC -> leuco-/lympho-/thrombocyto- penia are possible, anaemia of chronic disease, ESR raised in relation to activity, CRP normal,
U+Es --> will rise only in advanced renal disease, low albumin or high urine prot/creat ratio are early signs
Autoantibodies --> Full ANA screen and APS as well
Complement --> C3 & C4 will be reduced in active disease


Autoantibodies in SLE

SLE -- Anti-dsDNA (70%), anti-RO (40-60%), Anti-LA (15%), Anti-Sm (10-25% if white, 30-50% black), Anti-UI-RNP (30%),
Drug induced lupus -- Anti-histone


General Management of SLE

Avoid sunlight and reduce CVS RFs
Many pts will not require anything more than NSAIDs --> Topical corticosteroids are widely used for cutaneous SLE


Treatment of mild SLE symptoms

If NSAIDs are insufficient antimalarials (chloroquine or hydroxychloroquine) can be used (require eye checks)
IM or oral steroids for severe flares of arthritis/pluerisy/pericarditis -- these may require long term steroids


Treatment of severe SLE symptoms

Renal or cerebral disease --> high-dose oral steroids+ mycophenolate to induce remission -> azathioprine for maintenance
Severe haemolysis --> high-dose oral steroids
Anti-CD20 (rituximab) can be used in refractory cases


Disease progression in SLE

Episodic course with exacerbation separated by complete remission
Can be chronic & persistent
10yr survival is >90% - early deaths are renal/cerebral disease or infection -- later MI/CVA is more common
Progressive joint destruction is rarely seen but pts may develop deformity (ulnar deviation)


SLE and Pregnancy

Fertility is usually unaffected although there is a risk of recurrent miscarriage if APS antibodies are present. Exacerbations can occur during pregnancy and are frequent postpartum -- treatment should be continued and HTN particularly controlled. Pts with anti-RO or anti-LA have 2% risk of neonatal lupus syndrome


Jaccoud's arthropathy

a Rare manifestation of SLE where there is large joint deformity -- resembles RA clinically


Photosensitivity in SLE

Occurs in 40-50% of patients -- particularly associated with anti-RO positive pts
Prolonged exposure can lead to acute flare ups,


Raynaud's phenomenon in SLE

Common - similar basic RFs and due to disease and may precede the development of other symptoms by many years


Discoid Lupus

A benign form of lupus where only the skin is involved -- well defined erythematous plagues form on the face and lead to scarring and pigmentation


Shrinking lung syndrome

Pneumonitis or atelectasis which lead to restrictive defects reducing volume can occur -- thought to be neuromuscular in origin


Libman-sacks syndrome

Aseptic mitral valve endocarditis which is very rarely seen in SLE