What is an infiltrate?
Infiltrate in the lungs means that there is something seen that should not be there. Often this looks whiter then the dark lung. It is usually used to describe an abnormality that is not small and round like a nodule but more widespread and irregular.
No infiltrates seen on chest X-ray is most commonly used to say that there is no pneumonia seen. Infiltrate can also represent other abnormalities. We can not always tell what an abnormality is in the lung. Sometimes white areas that look like pneumonia can be other abnormalities.
What are some other conditions that can look like infiltrate?
Cancer can sometimes look like a an infiltrate. Cancer is usually a more chronic process and usually not associated with cough and fever like pneumonia. Cancer can also be associated with pneumonia from it obstructing a bronchus or air passage in the lung.
Infiltrate can also represent abnormalities related to more chronic lung diseases. An example would be allergic lung disease from external causes. These may be animal proteins, chemical, metals in addition to other causes.
Infiltrate can also represent scarring lung disease. We often can not tell if an abnormality is new and symptomatic unless we have old X-rays showing no change over time. Even collapsed portions of the lung can sometimes look like an infiltrate.
Does no infiltrate on chest X-ray mean all is ok?
While no infiltrate on chest X-ray is often meant to say that there is no pneumonia, there can still be one present. Sometimes pneumonias are not seen on X-ray because they are hidden or simply not detectable. Other pneumonias and respiratory infections don’t show up on X-rays. This is especially true with viral infections.
While no infiltrate seen on chest X-ray is a reassuring finding, it does not mean that you don’t have a lung infection. Your doctors may still need to treat an infection. Some pneumonias and infections show up later. Some pneumonias are only seen on CT scans. This is especially true for pneumonias in blind spots or those that are ground glass in density.
No infiltrate on chest X-ray therefore means that the lungs are clear. Most commonly the radiologist means there is no pneumonia seen on X-ray. It is important to remember that this does not mean you have no pneumonia or infection. It simply means we don’t see one. Further testing like CT may be needed.