Chest
Volume 125, Issue 1, January 2004, Pages 260-271
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Pulmonary Infiltrates in the Non-HIV-Infected Immunocompromised Patient: Etiologies, Diagnostic Strategies, and Outcomes

https://doi.org/10.1378/chest.125.1.260Get rights and content

Pulmonary complications remain a major cause of both morbidity and mortality in immunocompromised patients. When such individuals present with radiographic infiltrates, the clinician faces a diagnostic challenge. The differential diagnosis in this setting is broad and includes both infectious and noninfectious processes. Rarely are the radiographic findings classic for one disease, and most potential etiologies have overlapping clinical and radiographic appearances. In recent years, several themes have emerged in the literature on this topic. First, an aggressive approach to identifying a specific etiology is necessary; as a corollary, diagnostic delay increases the risk for mortality. Second, the evaluation of these infiltrates nearly always entails bronchoscopy. Bronchoscopy allows identification of some etiologies with certainty, and often allows for the exclusion of infectious agents even if the procedure is otherwise unrevealing. Third, early use of CT scanning regularly demonstrates lesions missed by plain radiography. Despite these advances, initial therapeutic interventions include the use of broad-spectrum antibiotics and other anti-infectives in order to ensure that the patients is receiving appropriate therapy. With the results of invasive testing, these treatments are then narrowed. Frustratingly, outcomes for immunocompromised patients with infiltrates remain poor.

Section snippets

Differential Diagnosis

The differential diagnosis for pulmonary infiltrates in the immunosuppressed patient is broad and includes both infectious and noninfectious etiologies. Table 1 lists potential etiologies for parenchymal lesions in these patients. The relative probability that any one explanation accounts for the infiltrates will be a function of the patient's underlying diagnosis, current immunosuppressive regimen, duration of immunosuppression, and prior therapies. For example, diffuse alveolar hemorrhage

Infectious Etiologies

Bacterial, fungal, viral, and mycobacterial pathogens may infect the lungs of immunosuppressed patients. In a prospective series3 of 200 immunocompromised patients with infiltrates, infectious agents were recovered from more than three fourths of subjects. An earlier study4 focusing solely on liver transplant recipients reported that 50% of infiltrates were infectious in origin. As a rule, these patients are at risk for infection with traditional nosocomial bacteria such as P aeruginosa and S

Noninfectious Etiologies

Noninfectious etiologies for pulmonary infiltrates in the immunosuppressed host are as diverse as the potential microbiologic etiologies. Furthermore, noninfectious processes are responsible for between 25 to 50% of infiltrates in these patients.342526 As with infectious agents, presenting signs and symptoms range from minor dyspnea to rapidly progressive respiratory failure. The initial clinical appearance is rarely helpful in identifying a specific cause. Many noninfectious causes of

Diagnostic Approach

The initial approach to the immunosuppressed patient with pulmonary infiltrates begins with a careful history focusing on current and prior immunosuppressive regimens. The aim of this is to quantitate the extent of the subject's immune dysregulation. Additionally, treatment with certain medications, as noted above, may raise concern for drug-induced lung injury. The temporal relationship between the onset of the pulmonary infiltrates and the initiation of immunosuppression routinely alters the

Outcomes

The evolution of pulmonary infiltrates in an immunocompromised patient is a worrisome sign. Each of the possible etiologies for pulmonary injury in these individuals is associated with a significant risk for mortality. In a review of 50 liver transplant recipients with pulmonary infiltrates, Torres et al4 noted a 32% mortality rate. Duran and coworkers55 noted a similar mortality from pulmonary complications following liver transplant. Although diagnostic delay independently increased the risk

Conclusion

Pulmonary infiltrates remain a vexing problem in the care of the immunosuppressed patient. Such infiltrates occur commonly following chemotherapy, HSCT, and SOT. With the increasing use of these treatment modalities and the growing potency of immunosuppressive regimens, physicians will more frequently be asked to evaluate and to care for these individuals. The differential diagnosis of pulmonary lesions in this setting is broad. It is important to search for both infectious and noninfectious

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    The opinions expressed herein are not to be construed as official or as reflecting the policies of either the Department of the Army or the Department of Defense.

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