| ). More recent studies have confirmed the reliability of 2-year stability in the assessment of benignancy in solid nodules, and shorter or longer periods of follow-up may be appropriate in selected subjects, depending on risk factors, nodule morphology, and accuracy of measurements (24). Thus, we recommend optionally discontinuing follow-up of well-defined solid nodules with benign morphology at 12–18 months if the nodule is accurately measurable and unequivocally stable. For subsolid nodules, longer-term follow-up is recommended (2).
For solitary solid noncalcified nodules measuring 6–8 mm in patients at high risk, an initial follow-up examination is recommended at 6–12 months and again at 18–24 months (grade 1B: strong recommendation, moderate quality evidence). This recommendation is based on an estimated average risk of malignancy of approximately 0.5%–2.0% for nodules in this size range and is derived from screening studies, most notably the PanCan, BCCA, and NELSON trials (6,7) Again, the precise intervals can be modified according to individual risk factors and preferences. In some patients in whom nodule stability remains uncertain, further surveillance may be required; however, two follow-up examinations should be sufficient to exclude growth in most subjects. For solitary solid noncalcified nodules larger than 8 mm in diameter, consider 3-month follow-up, work-up with combined positron emission tomography (PET) and CT (PET/CT), tissue sampling, or a combination thereof; any one of these options may be appropriate depending on size, morphology, comorbidity, and other factors. (grade 1A; strong recommendation, high-quality evidence). Although the average risk of cancer in an 8-mm solitary nodule is only approximately 3% depending on morphology and location, a considerably higher risk can be inferred in certain patients (25,26). As nodules become larger, their morphology becomes more distinct, and management should be strongly influenced by the appearance of the nodule rather than by size alone (Figs 5–7). Thus, both invasive and noninvasive management options are included in this article.  Figure 5: CT image shows a solid triangular subpleural nodule (arrow) with a linear extension to the pleural surface, typical of an intrapulmonary lymph node. No CT follow-up is recommended for such findings.  Figure 6: Transverse 1-mm CT section through the left upper lobe shows a suspicious solid spiculated nodule (arrow). Surgery revealed invasive adenocarcinoma. |