LIFE-THREATENING disease can develop in immunosuppressed patients due to a myriad of potential pathogens causing disease in virtually any organ system in the body. The prompt diagnosis and appropriate treatment of these infectious processes are essential to limiting their extent and duration and are vital to the prolongation of these patients' lives. Pneumonia is a particularly important cause of life-threatening infection in these populations because it is so frequent, because specific diagnoses can be established in a high percentage of cases, and because specific effective therapy is available for many of these diagnostic possibilities. Thus, the diagnosis and management of pneumonia in immunosuppressed patients are essential skills for any physician who deals with this patient population.
During the last decade, a number of important developments regarding pneumonitis have occurred: the range of recognized pulmonary pathogens has expanded, progress has been made in developing new noninvasive and invasive diagnostic techniques, and