In an effort to plug gaps in its original recommendations for the management of pulmonary nodules, the Fleischner Society issued six recommendations for follow-up of subsolid nodules detected by CT imaging. The recommendations were published online Oct. 15 in Radiology.

Although the guidelines issued in 2005 have been widely accepted, the initial recommendations did not specifically address subsolid pulmonary nodules. “[D]evelopment of a standardized approach to the interpretation and management of these lesions remain critically important,” wrote David P. Naidich, MD, from the department of radiology at New York University Medical Center in New York City, and colleagues.

The authors referred to increasing urgency for guidance regarding these nodules as peripheral adenocarcinomas appear to be increasing in frequency and account for 30 to 35 percent of all primary lung tumors. However, despite the need for a standardized approach, Naidich and colleagues referred to the diverse and controversial nature of the issues surrounding management of these nodules and suggested radiologists and their colleagues interpret the recommendations in light of the individual patient’s clinical history.

The authors provided six recommendations; three address solitary nodules and three focus on multiple nodules. The recommendations and corresponding rationale are:

1. Solitary, pure ground-glass nodules measuring 5 mm or less do not require follow-up surveillance CT. Many of the lesions represent incidental foci of adenomatous hyperplasia and are typically stable or extremely indolent over several years of follow-up. Estimates of doubling time and measurements of lesions of this size also are difficult and problematic.
2.  Solitary, pure ground-glass nodules larger than 5 mm require an initial follow-up CT exam in three months to determine persistence, followed by yearly surveillance CT exams for a minimum of three years if persistent and unchanged. These lesions often can be classified as preinvasive atypical adenomatous hyperplasia or adenocarcinoma in situ. Close monitoring enables early detection of changes, and may eliminate unnecessary surgery.
3. Solid ground-glass nodules, especially with a solid component larger than 5 mm, should be considered malignant until proven otherwise provided either growth or no change is seen at follow-up CT at three months. Previous research has demonstrated that part-solid, ground-glass nodules are more likely to be malignant than pure nodules, and should be approached with an aggressive diagnostic strategy.
4. Multiple well-defined ground-glass nodules all measuring 5 mm or less should be conservatively managed with CT exams at two and four years. Researchers have not yet established the likelihood of such lesions progressing into invasive adenocarcinoma; however, atypical adenomatous hyperplasia is a frequent additional finding among patients undergoing surgical resection of these nodules.
5. Patients with multiple pure ground-glass nodules, at least one of which is larger than 5 mm, and without a dominant lesion, should undergo follow-up CT at three months and annual surveillance CT for a minimum of three years. Similar to cases with a solitary pure ground-glass nodule larger than 5 mm, close monitoring enables early detection of changes and may eliminate unnecessary surgery.
6. In cases with multiple nodules and a dominant lesion(s), follow-up is determined by the dominant lesion. If an initial follow-up CT at three months confirms persistence, an aggressive approach to diagnosis and management is recommended. Although evidence regarding the exact clinical nature of such cancers is lacking, data suggest this presentation should be regarded with suspicion and patients with synchronous primary carcinoma may benefit from aggressive treatment.