Evaluation of solitary pulmonary nodule

A solitary pulmonary nodule is defined as a relatively round lesion that is <3 cm in diameter and completely surrounded by lung parenchyma. It is distinct from lung lesions >3 cm in diameter, which are considered lung masses. Traditionally, the definition of solitary pulmonary nodule has also excluded a ground-glass infiltrate seen on computed tomography (CT) scan, as this finding is commonly associated with bronchoalveolar cell carcinoma and does not fulfill the physical characteristics of a nodule.[1]Aoki T, Nakata H, Watanabe H, et al. Evolution of peripheral lung adenocarcinomas: CT findings correlated with histology and tumor doubling time. AJR Am J Roentgenol. 2000 Mar;174(3):763-8. http://www.ajronline.org/doi/full/10.2214/ajr.174.3.1740763 http://www.ncbi.nlm.nih.gov/pubmed/10701622?tool=bestpractice.com Most national guidelines make separate recommendations regarding the evaluation and management of solid pulmonary nodules, pure ground-glass nodules, and semi-solid nodules (which have both solid and ground-glass components). However, for all three, the risk of malignancy needs to be determined and action taken accordingly.

Management goals

The goals in managing a patient with a solitary pulmonary nodule are to distinguish the benign from the malignant nodule and, when malignancy is either confirmed or strongly suspected, to expedite treatment.

For solitary pulmonary nodules, established clinical features (e.g., patient age, smoking status) and radiographic findings (e.g., calcification, growth rate, size) help determine a probability of malignancy. These factors can be used to inform risk calculations based on models derived from large screening studies.[2]González Maldonado S, Delorme S, Hüsing A, et al. Evaluation of prediction models for identifying malignancy in pulmonary nodules detected via low-dose computed tomography. JAMA Netw Open. 2020 Feb 5;3(2):e1921221. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2760895 http://www.ncbi.nlm.nih.gov/pubmed/32058555?tool=bestpractice.com [3]McWilliams A, Tammemagi MC, Mayo JR, et al. Probability of cancer in pulmonary nodules detected on first screening CT. N Engl J Med. 2013 Sep 5;369(10):910-9. https://www.nejm.org/doi/10.1056/NEJMoa1214726?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200www.ncbi.nlm.nih.gov http://www.ncbi.nlm.nih.gov/pubmed/24004118?tool=bestpractice.com ​​​ If risk is deemed to be sufficiently high, noninvasive and/or invasive testing is used to more accurately determine the probability of malignancy to a level that enables a decision to be made regarding observation or resection. Therefore, the proper use of these tests mandates knowledge about their performance characteristics.