By Dr. Katie E. Golden, MD

No one wants to hear the words “You have a spot on your lungs.” But this is a common occurrence in the emergency department (ED), where people frequently get a chest Xray as part of their work up. Usually, your provider is referring to something called a pulmonary nodule. Sometimes they are a harmless, temporary change in the appearance of lung tissue. Other times, they can be an early sign of developing lung cancer. But before your mind goes to the worst case scenario, it helps to understand exactly what these are, and what to do if you have one.

What is a pulmonary nodule?

A pulmonary nodule is a small area of tissue in the lungs that appears more dense than normal lung tissue. Pulmonary means lung, and nodule is a medical term that means a small collection of cells that appear abnormal.

They are typically very small, and do not cause any symptoms.

Pulmonary nodules can be seen on both X-ray and CT scans. They are usually what we call an ‘incidental finding.’ In other words, they are typically not relevant to the symptoms or medical condition that brought you into the ED. But it is important to note them so you can get the right follow-up. (More on this a little later)

What causes a pulmonary nodule?

Pulmonary nodules are common in the lungs. In the general population, it is estimated that anywhere from 2 to 24% of people have them. 

The causes of pulmonary nodules include:

    • Infections: Many different types of infections can cause pulmonary nodules. But the types of infections that do this tend to be more rare — like certain types of fungal infections and parasites. More common pneumonias, from bacteria and viruses, tend to look different on a chest X-ray. 
    • Scars: Prior infections can leave behind scar tissue that looks like a nodule. So can prior exposure to respiratory irritants.
    • Inflammation: Certain inflammatory conditions can affect the lung. Examples include sarcoidosis and rheumatoid arthritis. And any condition that leads to vasculitis — a type of inflammation of the blood vessels — can also cause nodules.
  • Congenital abnormalities: Things like cysts (small collections of fluid) and arteriovenous malformations (a small tangle of blood vessels) can look like nodules. Many times, people are born with these and they don’t cause any problems.
    • Mucus: When mucus collects in the lower airways, it can cause something called mucous plugging. This is when the mucus prevents the lungs from aerating properly, and so that area can look more dense than normal lung tissue.
  • Atelectasis: This is a medical term that means the bottom part of the lung gets smooshed. This can happen if someone is not taking deep breaths, or if they have been laying down for a long time. Similar to mucus plugging, the smooshed tissue appears more dense than normal tissue. 

And of course, cancer can also appear as a nodule on lung imaging. This is why these little guys get so much attention.

Does a pulmonary nodule mean I could have cancer?

We take pulmonary nodules seriously in the event they are the first sign of lung cancer.  Several different types of cancer can appear as pulmonary nodules:

  • Lung cancer
  • Metastatic cancer (cancer s from another area of the body that has spread to the lungs)
  • Lymphomas
  • Sarcomas
  • Rare carcinoid tumors

The likelihood that a pulmonary nodule is cancer increases if you have risk factors for cancer. These include:

  • Older age
  • Current or prior smoking
  • Family history of lung cancer
  • Personal history of other types of cancer

But it’s important to know that even if you are at higher risk, this doesn’t mean you have cancer. Less than 5% of cases turn out to be cancer. 

What should I do if I have a pulmonary nodule?

Even though most nodules will not be cancer, it is important to follow up with your provider to rule it out. And this doesn’t necessarily mean you will need more testing. In many cases, they can rule it out based on your risk factors and the way the nodule appears on the image.

People with increased risk for lung cancer may need more testing. This is also true for nodules that appear particularly large or irregular. In these cases, your provider may recommend more testing: 

  • For most people, this means a repeat CT scan in 3 to 6 months to see if the nodule has changed or grown. 
  • For nodules that are more suspicious, a PET scan or even a biopsy may be the next step. A PET scan is a special type of scan that is particularly good at picking up cancer. A biopsy is when someone collects a small sample of the nodule for testing.

The take home point here is that if you have a pulmonary nodule, don’t lose sleep worrying that you have cancer. The likelihood is low. The next step is to follow up with your regular provider, who can help you figure out if any more testing is needed.