Respiratory involvement in systemic lupus erythematosus.

Respiratory involvement in systemic lupus erythematosus (SLE) is not as well-known as the cutaneous, rheumatological and renal manifestations. It occurs frequently but the diagnosis may be difficult because of the heterogeneity of the anatomical and clinical presentations. A precise diagnosis is crucial as new immunosuppressive drugs have considerably improved the prognosis. The pathology involves genetic, endocrine, environmental, pharmacological and immunological factors with a cytotoxic reaction of auto-antibodies against complement, a circulating immune complex reaction and a hyperactivity of B lymphocytes. Respiratory involvement in SLE can be classified in five groups based on the anatomy: pleural involvement, infiltrating pneumonia (lymphoid interstitial pneumonia, bronchiolitis obliterans with organizing pneumonia and acute lupus pneumonitis), airways involvement (upper airways, bronchi), vascular involvement (pulmonary hypertension, acute reversible hypoxaemia, alveolar haemorrhage, and antiphospholipid syndrome), muscular and diaphragmatic involvement (shrinking lung syndrome).Treatment is based, depending upon the type of involvement and its severity, on steroids which may be combined with immunosuppressants and plasmapherisis.