) (3,36,41,42). Again, we would emphasize that these guidelines are not intended to preclude either shorter or longer term follow-up in individual subjects, when deemed clinically appropriate (43).
 Figure 11a: (a) Transverse 1-mm CT section through the left upper lobe shows an indeterminate 10-mm ground-glass nodule (arrow). (b) Follow-up CT image after 4 months shows interval resolution without treatment, consistent with a benign cause, such as focal infection.  Figure 11b: (a) Transverse 1-mm CT section through the left upper lobe shows an indeterminate 10-mm ground-glass nodule (arrow). (b) Follow-up CT image after 4 months shows interval resolution without treatment, consistent with a benign cause, such as focal infection. Recommendation 4: solitary part-solid lung nodules.—For solitary part-solid nodules smaller than 6 mm, no routine follow-up is recommended (grade 1C; strong recommendation, low- or very-low-quality evidence). In practice, discrete solid components cannot be reliably defined in such small nodules, and they should be treated similar to the way in which pure ground-glass lesions of equivalent size are treated (see Recommendation 3, which was described previously). For solitary part-solid nodules 6 mm or larger with a solid component less than 6 mm in diameter, follow-up is recommended at 3–6 months and then annually for a minimum of 5 years. Although part-solid nodules have a high likelihood of malignancy, nodules with a solid component smaller than 6 mm typically represent either adenocarcinoma in situ or minimally invasive adenocarcinoma rather than invasive adenocarcinoma (42,43). Additionally, part-solid nodules may be due to transient infections and may resolve after short-term follow-up (Fig 12 |