Pneumonia in Immunocompromised Patients

Due to longer survival of patients with cancer, better recognition and understanding of immunocompromising conditions, and emerging immune-modulating therapies for malignant and nonmalignant diseases, the number of immunocompromised individuals has increased. Immunocompromised patients require complex, often individualized, evaluation and treatment of an expanded spectrum of pathogens. Pneumonia is a leading cause of death due to infectious disease in these patients, and identification of the pathogen is key to providing appropriate therapy. One important factor in evaluating an immunocompromised patient with pneumonia is the type of immunocompromise, because this will help determine the potential opportunistic agents that should be included in the differential diagnosis. Radiologists can play a vital role in the diagnosis of a wide range of pulmonary diseases associated with immunocompromise, including many opportunistic pulmonary infections, by recognizing key imaging features. The authors summarize the types of immunocompromise encountered in different clinical settings and associate these with specific opportunistic organisms, describe patterns of disease seen in patients with HIV infection with different CD4 cell counts, and describe the imaging appearance of viral and fungal infections in patients with neutropenia. ^©RSNA, 2025.