From the Guidelines
Infiltrates on a chest x-ray are areas of increased density or opacity in the lung tissue that appear as white or gray patches on the radiographic image, representing accumulation of fluid, cells, or other substances within the air spaces or interstitial tissues of the lungs, as noted in a study published in 2021 1.
Definition and Causes
Infiltrates can result from various conditions including pneumonia (bacterial, viral, or fungal infections), pulmonary edema (fluid in the lungs), hemorrhage (bleeding into the lungs), inflammatory processes, or malignancies.
- The pattern, distribution, and characteristics of infiltrates help radiologists and clinicians determine the underlying cause.
- For example, lobar infiltrates that affect an entire lobe suggest bacterial pneumonia, while diffuse bilateral infiltrates might indicate pulmonary edema or viral pneumonia.
- Patchy infiltrates scattered throughout both lungs could represent bronchopneumonia or an atypical infection.
Diagnostic Approach
The presence of infiltrates typically indicates active disease requiring further investigation and often treatment, depending on the underlying cause.
- Clinical correlation with symptoms, laboratory findings, and sometimes additional imaging is necessary for accurate diagnosis and appropriate management, as suggested by guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia 1.
- A study published in 2019 noted that the yield of chest radiographs is very low in patients with acute cough illness, particularly among those for whom the physician did not think a chest radiograph was necessary 1.
- However, in certain cases, such as when a new infiltrate is suspected, chest radiography can provide valuable information to guide invasive diagnostic approaches and detect pleural effusion, as mentioned in a study from 2001 1.
Recent Guidelines and Recommendations
A position paper from the Fleischner Society published in 2021 proposed diagnostic criteria for drug-related pneumonitis, including newly identified pulmonary parenchymal opacities at CT or chest radiography, temporal association of presentation with the initiation of a systemic therapeutic agent, and exclusion of other likely causes 1.
- These criteria highlight the importance of considering the clinical context and excluding other possible causes when evaluating infiltrates on a chest x-ray.
- The American Thoracic Society clinical practice guideline published in 2012 also emphasized the importance of clinical correlation and additional imaging in the evaluation of suspected interstitial lung disease 1.
From the Research
Definition of Infiltrates on a Chest X-ray
Infiltrates on a chest x-ray refer to abnormal substances or cells that have entered the lung tissue, which can be a sign of various lung diseases or conditions.
Causes and Appearances of Infiltrates
- Infiltrates can be caused by bacterial pneumonia, as seen in a case of Achromobacter xylosoxidans denitrificans pneumonia, where chest X-ray demonstrated right-sided infiltrates 2.
- They can also be a result of other pathological processes, such as diffuse lung disease, which can present with a wide array of radiological patterns 3.
- In some cases, infiltrates on a chest x-ray can be due to unusual causes, such as mitral regurgitation, where the regurgitant jet can cause lobar edema 4.
- The appearance of infiltrates on a chest x-ray can vary, ranging from diffuse small nodules or ground glass densities to reticulonodular shadows or honeycombing 5.
Clinical Significance of Infiltrates
- The presence of infiltrates on a chest x-ray can be associated with adverse outcomes, such as longer hospital stays, intensive care admission, pulmonary complications, and higher mortality rates 6.
- The detection of pulmonary infiltrate or bacteraemia can indicate a more severe disease course and higher inflammation, which can partly mediate the outcome gradient in patients with pneumococcal lower respiratory tract infection 6.