Paediatrics: Systemic lupus erythematosus

Systemic lupus erythematosus

Complex, multisystem autoimmune disorder affecting adolescents (rare in younger children; female:male ratio 20:1). Commoner and more severe in Afro-Caribbean, Hispanic, and Far Eastern girls.

The ARA criteria are helpful (90% sensitivity 97% specificity), but less reliable in early disease.¹ One of the ‘great mimics’ of other conditions.

The revised ARA criteria for the classification of SLE¹

SLE is diagnosed if 4 of the 11 features present simultaneously or serially:

•   Malar rash

•   Discoid rash

•   Photosensitivity

•   Mouth ulcers

•   Arthritis (non-erosive)

•   Serositis: pleurisy or pericarditis

•   Renal disease: persistent proteinuria >0.5g/24hr or cellular casts

•   Neurological disorder: psychosis or seizures in absence of known precipitants

•   Haematological abnormality: haemolytic anaemia or leucopenia <4.0 x 10⁹/L on 2 or more occasions or thrombocytopenia <100 x 10⁹/L

•   Immunological: raised anti DNA binding antibody, anti-Smith antibody, and/or +ve antiphospholipid antibodies

•   Antinuclear antibody

Clinical features

The presenting complaint may affect any organ system.

•   Non-specific constitutional symptoms common: low grade fever, weight loss, fatigue, anorexia, and lymphadenopathy.

•   Mucocutaneous problems: hair loss (scarring and non-scarring alopecia); mouth ulcers; photosensitivity (50%); Raynaud’s phenomenon (90%); malar ‘butterfly’ rash over bridge of nose and sparing nasolabial folds; discoid lesions; livido reticularis; urticarial rashes; purpuric rashes; digital vasculitis.

•   Musculoskeletal (90%): polyarthritis resembling rheumatoid arthritis (non-erosive); tendonitis; arthralgia; myalgia; myositis (5%); aseptic necrosis.

•   Cardiovascular: pericarditis (silent or rapidly constrictive); myositis, valvulitis with endocarditis (Libman–Sachs).

•   Pulmonary: pleurisy; pleural effusions; haemoptysis from pulmonary vasculitis; interstitial fibrosis; pneumonitis.

•   Renal: hypertension; proteinuria; nephritis; nephrotic syndrome; renal failure.

Haematological: anaemia (normochromic normocytic, Coombs +ve haemolytic, renal failure, drug-related); leucopenia and lymphopenia common (80%); thrombocytopenia (20%) chronic, rarely aggressive.

• Neurological: migraine (40%); mood disorders (anxiety, depression, emotional liability (70%)); psychoses (rare); seizures (rare); peripheral neuropathies (10%).

• Careful drug history: especially tetracyclines for acne (+ve antihistone antibodies).

Investigations

FBC, LFTs; renal function; BP measurement; urinalysis; ANA (99%), dsD-NA (40% , but specific for SLE); RF; coagulation screen; anticardiolipin and antiphospholipid antibodies. ESR may be raised; CRP low unless serositis or infection; C3, C4 low in active disease.

Management: in specialist clinic

• General: avoid sun exposure and use sun-screen; treat hypertension; and minimize long-term cardiovascular risks. Use ACE inhibitors for nephroprotection for proteinuria.

• Target and treat aggressively affected organs.

• NSAIDs for musculoskeletal symptoms.

• Hydroxychloroquine for fatigue, rashes, and arthritis.

• Prednisolone and steroid-sparing drugs (azathioprine (AZA), MTX, mycophenolate mofetil (MMF)) for other severe manifestations.

• Prednisolone and cyclophosphamide for active nephritis; then AZA or MMF.

• Experimental treatments for refractory cases: rituximab; autologous stem cell replacement.

Prognosis

• Very variable between ethnic groups. Overall 5-yr survival 90% with death from unremitting active disease or immunosuppression.

• Prognosis worse for those with nephritis (60% after 15yrs).

Bimodal survival curve with long-term increased risk of cardiovascular disease.