Differential diagnosis of diffuse alveolar haemorrhage in immunocompromised patients

Purpose of review Diffuse alveolar haemorrhage (DAH) is a life-threatening medical emergency in immunocompromised and immunocompetent patients characterized by haemoptysis, anaemia, acute respiratory failure and diffuse pulmonary infiltrates on radiologic examination. This review describes DAH imaging features, causes and main differential diagnosis. Recent findings In immunosuppressed patients, DAH occurs most frequently in haematologic neoplasms, after haematopoietic stem cell transplantation or solid organ transplantation, secondary to drug reaction or infection, and associated with AIDS. However, differential diagnoses of all of these conditions include several conditions with similar findings. Imaging patterns of DAH do not differ significantly from those of conditions included in the main differential diagnosis. The differential diagnosis depends on the patient's immunity status. In immunocompromised patients, infection and lung injury of other causes must be considered.