Pulmonary manifestations in systemic lupus erythematosus: pleural involvement, acute pneumonitis, chronic interstitial lung disease and diffuse alveolar hemorrhage.

Systemic lupus erythematosus is the diffuse autoimmune connective tissue disease that most frequently involves pulmonary involvement, affecting 20% of 90% of the patients. The percentage varies depending on the defining criteria (symptoms, pulmonary tests or histopathological studies). At least once during the disease course, 50% of those affected have pleural and/or pulmonary manifestations, which are associated with higher morbidity and mortality. Pulmonary involvement has no correlation with lupus activity biomarkers, and it is necessary to rule out infectious processes in the initial approach. Bacterial infection is most frequently the cause of lung involvement in lupus and is one of the most important causes of death. Pulmonary involvement is considered to be primary when it is associated with disease activity, and secondary when other causes participate. Drugs have been reported to be associated with pulmonary damage, including interstitial disease. The incidence of malignant lung diseases is increased in systemic lupus erythematosus. Treatment depends on the type and severity of pulmonary involvement.