 ARI constitutes a group of signs and symptoms that develop over a brief interval (hours to weeks), some of which are constitutional (eg, fever, chills, weight loss), and some of which are organ specific (eg, cough, shortness of in complications encountered in breath, chest pain). The respiratory system is frequently involved immunocompromised states. in immunosuppressed patients, and many progress along a rapid and potentially fatal course [1,2]. Noninfectious causes should also be considered when an immunocompromised patient presents with ARI, including such entities as pulmonary edema, drug-induced lung disease, atelectasis, malignancy, radiation-induced lung disease, pulmonary hemorrhage, diffuse alveolar damage, organizing pneumonia, lung transplant rejection, and pulmonary thromboembolic disease [2]. Discussion of Procedures by Variant Variant 1: Acute respiratory illness in immunocompromised patients. Cough, dyspnea, chest pain, or fever. Initial imaging. Radiography Chest Chest radiography is the initial imaging modality of choice for the diagnostic assessment of immunocompromised patients presenting with ARI [3]. The chest radiograph typically shows the presence and extent of pulmonary infection, although radiographs can be normal in up to 10% of patients with proven disease [4]. The pattern and distribution of abnormalities on the chest radiograph, along with changes on serial radiographic examinations, can aid in formulating a differential diagnosis. Chest radiographs may also show the presence of complications of infectious pneumonia, such as empyema or abscess [3,5]. The well-known limitations of chest radiography; however, are the lack of specificity with regard to specific pathogens and overall low sensitivity for detecting subtle abnormalities in immunocompromised patients with symptomatic disease [1]. aResearch Author, University of Southern California Keck School of Medicine, Los Angeles, California.
Acute Respiratory Illness in Immunocompromised Patients.  ARI constitutes a group of signs and symptoms that develop over a brief interval (hours to weeks), some of which are constitutional (eg, fever, chills, weight loss), and some of which are organ specific (eg, cough, shortness of in complications encountered in breath, chest pain). The respiratory system is frequently involved immunocompromised states. in immunosuppressed patients, and many progress along a rapid and potentially fatal course [1,2]. Noninfectious causes should also be considered when an immunocompromised patient presents with ARI, including such entities as pulmonary edema, drug-induced lung disease, atelectasis, malignancy, radiation-induced lung disease, pulmonary hemorrhage, diffuse alveolar damage, organizing pneumonia, lung transplant rejection, and pulmonary thromboembolic disease [2]. Discussion of Procedures by Variant Variant 1: Acute respiratory illness in immunocompromised patients. Cough, dyspnea, chest pain, or fever. Initial imaging. Radiography Chest Chest radiography is the initial imaging modality of choice for the diagnostic assessment of immunocompromised patients presenting with ARI [3]. The chest radiograph typically shows the presence and extent of pulmonary infection, although radiographs can be normal in up to 10% of patients with proven disease [4]. The pattern and distribution of abnormalities on the chest radiograph, along with changes on serial radiographic examinations, can aid in formulating a differential diagnosis. Chest radiographs may also show the presence of complications of infectious pneumonia, such as empyema or abscess [3,5]. The well-known limitations of chest radiography; however, are the lack of specificity with regard to specific pathogens and overall low sensitivity for detecting subtle abnormalities in immunocompromised patients with symptomatic disease [1]. aResearch Author, University of Southern California Keck School of Medicine, Los Angeles, California.