Some CT scans that are done for parts of your body other than the lungs include portions of the lungs. Radiologists who interpret the CT will look at all the anatomy even if the CT scan is not of the lungs. They are responsible for making sure there are no abnormalities on everything that is included in the scan, It sometimes happen that the most lower or upper part of the scan includes a lung nodule. We can not see it all because the scan stopped at that point.
What kind of scans include the lungs?
Most commonly, I see this with CT scans of the abdomen which include the lower parts of the lungs and neck CTs which include the upper parts. It is often surprising to hear that a nodule was found on a test for the abdomen or neck, but every CT scan of the abdomen and neck includes the lungs. Sometimes we see abnormalities like pneumonia and even cancer.
What should be done next after a partially visualized nodule?
A nodule that is partially seen should be evaluated with a dedicated Chest CT. This will allow us to see the entire nodule. We can measure the size accurately. We can also look at the appearance in more detail to see if there are any features that point to a benign cause. The chest CT will also allow us to see if there are any other abnormalities in the chest. Is this the only nodule or are there others? Are there enlarged lymph nodes? Is there an infection elsewhere in the lungs?
What can a nodule be?
The main concern with a nodule or spot in the lungs is cancer. However, there are many benign causes of nodules that can be ignored. Prior infections and scars can look like nodules. The bigger the nodule, the more concern we have for cancer. If you have smoked in the past, than this becomes more of a concern. Prior scans are also helpful to determine the cause. If you have an old scan from years ago that shows little to no change than the nodule is likely benign.
What do we do next for a nodule?
If the chest CT does not come to a conclusion about whether a nodule is benign or cancerous than further workup will be needed. This may include a follow up scan to see if it grows. A PET scan is done to see if the nodule is metabolically active and therefore more likely to be cancerous. Sometimes a biopsy is done. A specialist in lung disease may manage your care and determine the best plan.