[The pulmonary-renal syndrome: a diagnostic and therapeutic emergency for the internist and the intensivist].

The pulmonary-renal syndrome is a rare and life-threatening condition. It is defined as the association of a diffuse alveolar hemorrhage and a rapidly progressive glomerulonephritis. The characteristic histological lesion common to all underlying diseases is a necrotizing and crescentic glomerulonephritis. The pulmonary-renal syndrome is a diagnostic and therapeutic emergency: any delay in its management will lead to death or serious functional damage as pulmonary and renal impairment. ANCA-associated vasculitis and Goodpasture's disease are the main disorders associated to pulmonary-renal syndrome. More rarely systemic lupus, cryoglobulinaemia, Henoch-Schonlein purpura or subacute endocarditis may induce a pulmonary-renal syndrome. Differential diagnosis can sometimes be difficult, highlighting some ambiguity in the definition of the syndrome. Initial treatment usually associates systemic corticosteroid, cyclophosphamide and plasma exchange. The role of biotherapy as first line therapy remains to be determined.