Diffuse lung disease in the immunocompromised non-HIV patient

Physicians are encountering an increasing number of patients with various levels of immunosuppression, such as patients with AIDS, transplant recipients, patients on immunosuppressive therapy, and those with congenital immune defects and malignancy. This results in a greater diagnostic dilemma for the medical community because of the significant increased risk of opportunistic infections and noninfectious complications, as well as a more aggressive clinical course with typical pathogens. [figure: see text] Furthermore, it is not just the pathogens that are changing but also their clinical and radiographic presentations. The radiologist has a large role in not only detecting the presence of disease but also in narrowing the differential possibilities. This can be an overwhelming task given the wide variety of presentations of diseases on radiographs. However, by understanding the level and degree of the patient's immunosuppression, the radiologist may anticipate the most likely pulmonary complications. By using the radiographic morphology, distribution, and temporal evolution of the abnormalities, a manageable differential diagnosis can be created for referring clinicians.