Systemic diseases and the lung

Pulmonary complications may be encountered with many systemic diseases. This article discusses several such complications associated with: vasculitis (Wegener's granulomatosis, Churg–Strauss syndrome); connective tissue diseases (systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus, polymyositis and dermatomyositis, Sjögren's syndrome, ankylosing spondylitis); diseases of the liver (hepatopulmonary and portopulmonary syndrome) and gastrointestinal tract (inflammatory bowel disease); neurological disease (motor neurone disease, Guillain–Barré syndrome); endocrine disease (obesity and thyroid disorders); haematological disease (lymphoma and common variable immunodeficiency); and orphan lung diseases (lymphangioleiomyomatosis, pulmonary Langerhans' cell histiocytosis, alveolar proteinosis, pulmonary amyloidosis, hereditary haemorrhagic telangiectasia, Behçet's disease).Different features of individual diseases are discussed such as typical clinical features, physiology and radiology, and finally an approach to management of such cases. Where relevant there is also discussion of drug-induced lung disease, which can sometimes be difficult to distinguish from disease-related pulmonary disease per se.