Pulmonary Nodule on CT

The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 8, 2013


My wife was recently notified of the possibility of a "small malignancy" in the right upper lobe of her lung. The mass was categorized as a "subpleural, subcentimeter (8mm) pulmonary nodule" confirmed by a contrast CT scan. She is a smoker, age 46. We have seen a thoracic surgeon for consultation, and were told that nothing should be done right now, just monitoring by CT scans every three months. Presumably we are to wait for something to happen, and then do something, but we want to act now. Any suggestions?


Anil Vachani, MD, Pulmonologist at Penn Medicine, responds:

The majority of pulmonary nodules discovered on CT scan are ultimately determined to be benign. Unfortunately, an absolute diagnosis cannot be established without a biopsy and histological evaluation. Although I cannot specifically comment on this case without reviewing your wife's history and films, one approach is to follow the algorithm that has been established by the International ELCAP study. Many physicians use a similar algorithm. In this study, for patients with a solid, non-calcified nodule between 5 mm and 15 mm, the preferred option was to obtain a repeat CT scan in 3 months. Alternatively, one could obtain a PET scan and if positive, consider performing a biopsy. It should be noted that the sensitivity of PET scan is lower for smaller nodules, particularly those smaller than 8-10 mm.

Some things we have learned about pulmonary nodules through several recent studies include:

  • Approximately 50% of all smokers over age 50 have at least one pulmonary nodule, and when followed by CT scan annually, 10% will develop a new nodule during or after the first year.
  • The probability that a nodule is malignant increases with increasing size of the nodule. Even in smokers, the percentage of all nodules smaller than 4 mm that will eventually be confirmed as lung cancer is less than 1%. For those nodules between 5.0-9.0 mm, the percentage is approximately 5-10%.
  • A smoker's risk of developing cancer is related to the amount they smoke (number of cigarettes/day and over how many years they smoked).
  • The risk of a nodule being cancerous increases with age.

Some physicians use the Fleischner Guidelines that are summarized below. These guidelines for the management of small pulmonary nodules have been developed by the Fleischner Society, a professional society for chest radiologists:

Fleischner Guidelines