Opportunistic pneumonia

Abstract

Patients with abnormalities in their immune defense mechanisms are frequently encountered in the practice of medicine. These patients have increased susceptibility to infections that often involve the lung. Many of these infections are caused by opportunistic organisms that typically do not produce disease in individuals with a normally functioning immune system. To complicate the evaluation of these patients, they frequently develop noninfectious lung disease, which can have a radiographic appearance that is similar to infection. The purpose of this article is to present an approach to the evaluation of chest radiographic abnormalities in the immunocompromised patient with suspected pneumonia. Clinical information that is pertinent in the evaluation of immunocompromised patients is discussed. The various chest radiographic patterns seen in both infectious and noninfectious diseases that occur in the immunocompromised patient are reviewed. Integration of clinical information and radiographic findings in the development of a list of differential diagnoses is stressed.