Pulmonary infections in immunocompromised hosts: The importance of correlating the conventional radiologic appearance with the clinical setting

The lung is one of the most frequently involved organs in a variety of complications in the immunocompromised host. Among the pulmonary complications that occur in this kind of patient infection is the most common is associated with high morbidity mortality. Although chest radiography computed tomography (CT) are essential diagnostic tools radiologists often have difficulty in establishing the correct diagnosis on the basis of radiologic findings alone. The reasons are that the immunocompromised host is potentially susceptible to infection from many different microorganisms that radiologic findings are seldom specific for the detection of a particular pathogen. Experience has shown that a particular clinical setting predisposes patients to infection by particular pathogens. The setting comprises (a) the specific epidemiologic or environmental exposure (b) the type of underlying immune defect (c) the duration severity of immune compromise (d) the progression rate pattern of the radiologic abnormality. Correlating the radiologic appearance with the clinical setting can expedite diagnosis appropriate therapy. In this review the authors describe the clinical settings that are helpful in choosing the radiologic approach to treatment of the immunocompromised host who presents with suspected pulmonary infection.