Intrapulmonary Lymph Nodes

One of the main reasons people go into radiology is the promise that one day, if they play their cards right, they can spend half their day doing nothing but hunting nodules on chest CTs ordered for "cough." Not uncommonly, we come across peripheral nodules that may or may not be intrapulmonary lymph nodes.

At least two papers (one from our institution back in 1996, and a recent one from NYC) have described the CT appearance of these intrapulmonary lymph nodes. They tend to be predominantly in the lower lobes and in the right middle lobe, all below the carina.

They can range in size from a few mm to 9 mm and are located within 20 mm of the chest wall, with the ones farthest away from the chest wall abutting fissures. The nodules are sharply defined and uncalcified. They may have a discrete thin tag or thickened interlobular septum extending to the pleural surface.

References

• Bankoff MS, McEniff NJ, Bhadelia RA, Garcia-Moliner M, Daly BD. Prevalence of pathologically proven intrapulmonary lymph nodes and their appearance on CT. AJR Am J Roentgenol. 1996 Sep;167(3):629-30.
• Shaham D, Vazquez M, Bogot NR, Henschke CI, Yankelevitz DF. CT features of intrapulmonary lymph nodes confirmed by cytology. Clin Imaging. 2010 May-Jun;34(3):185-90.