Acute lung disease in the immunocompromised host.

The immunocompromised host is an individual with a decreased defense mechanism or immunity. Pulmonary complications commonly seen in these patients include infections, neoplasms, drug-induced lung disease, and pulmonary hemorrhage. High-resolution CT plays an invaluable role in confirming the presence of pulmonary disease and narrowing down the differential diagnosis in this group of patients. It also is helpful as a guide to the optimal type and site of biopsy. The pattern and prevalence of disease varies considerably between the AIDS and the non-AIDS group, and therefore, these two groups are considered separately.