Noninfectious Lung Infiltrates That May Be Confused with Pneumonia in the Cancer Patient

Abstract

The clinical and radiographic presentation of noninfectious pulmonary disease can often mimic pneumonia in the cancer patient. This chapter provides an overview of some of the most commonly observed noninfectious entities which may be observed in the immunocompromised host with cancer. Hydrostatic and nonhydrostatic pulmonary edema, as well as transfusion-related acute lung injury, may cause bilateral airspace opacification that may be confused with an infectious process. Chemotherapy induced lung injury can occur with many classes of chemotherapeutic agents and requires a high index of clinical suspicion for diagnosis. It often results in distinct patterns of pathologic injury, which may present acutely, subacutely or chronically, and in some cases, up to years after initial administration of the chemotherapeutic agent. Radiation induced lung injury often causes a distinct pattern of radiographic abnormalities, which may occur many months after the initial radiation exposure. In hematopoietic stem cell transplant recipients, many pulmonary diagnoses, such as engraftment syndrome, idiopathic pneumonia syndrome and diffuse alveolar hemorrhage (occurring early) and cryptogenic organizing pneumonia (occurring late), can mimic infectious pneumonias. Small airway mucus impaction can present with tree-in-bud opacities on chest CT and mimics infectious bronchiolitis. It may resolve with only pulmonary hygiene maneuvers. A combined approach involving careful review of the patient's history, pattern of infiltrates on chest CT, and the use of bronchoscopy with bronchoalveolar lavage with or without transbronchial lung biopsy can often help provide clues to the noninfectious diagnosis.