The prevalence of systemic lupus erythematosus (SLE) is 28 per 100,000. The 
disease is most common in people of Caribbean or Asian descent. SLE mainly 
affects adults and is common in women between the ages of 20 and 40 years, with 
a female to male ratio of 9:1. The pathogenesis is multifactorial and 
encompasses multiple immunological, vascular and inflammatory processes. 
Diagnosing SLE can be challenging because of the myriad of clinical features and 
substantial variability between patients. Cutaneous involvement is present in 
about 60% of cases and typically manifests as a malar or butterfly rash. Joint 
involvement is inflammatory in nature with arthralgia, arthritis and/or 
tendinitis and occurs in about 90% of patients with SLE. Cardiorespiratory 
symptoms are common with chest pain on inspiration due to lupus-induced pleurisy 
or pericarditis, which may be associated with effusions. Lupus 
glomerulonephritis is one of the most important systemic complications, 
occurring in about 30% of patients with SLE in the UK. Careful screening tests 
for renal disease need to be undertaken as it is asymptomatic. The diagnosis of 
SLE is traditionally based on a combination of clinical features and laboratory 
findings and any patient with suspected clinical features of lupus should be 
investigated for the presence of autoantibodies. Treatment often includes 
corticosteroids, by various routes, at different points in disease management. 
In addition, some experts advocate the use of hydroxychloroquine, an 
antimalarial, as a principal drug in all SLE patients. It is beneficial in the 
management of mucocutaneous, musculoskeletal, serosal and constitutional 
symptoms.