[Differential diagnosis of diffuse pulmonary haemorrhage]

Diffuse alveolar haemorrhage (DAH) denotes a diffuse intra-alveolar bleeding from small vessels as a result of severe damage of the alveolocapillary membrane of the lungs. These are comparatively rare, but than often life threatening events. The differential diagnosis is broad and comprises immunologic as well as toxic, infectious, hemodynamic, neoplastic and physical causes. DAH may be a manifestation of systemic diseases, as well as a result of an injury restricted to the lungs. The most frequent systemic diseases, that cause DAH are the so-called small vessel vasculititis-microscopic polyangiitis and Wegener's granulomatosis. More rarely Goodpasture's syndrome and systemic lupus erythematosus are causal. Alongside the immunologic processes mainly diseases with increased left-ventricular preload, infections and side effects of drugs have to be kept in mind. This review summarizes the differential diagnostic spectrum and the diagnostic workup of patients with DAH. Because early aggressive treatment can be life-saving, early and aimed diagnostics is essential.