–57). However, a large solid component can also be seen in transient part-solid nodules (44,58).
 Figure 13a: (a) Transverse 1-mm CT section through the superior segment of the right lower lobe shows a highly suspicious (large size, ground-glass appearance, and solid morphology) part-solid nodule (arrow). (b) Follow-up image obtained 3 months after a shows progressive increase in the size of the solid component. Surgery revealed invasive adenocarcinoma.  Figure 13b: (a) Transverse 1-mm CT section through the superior segment of the right lower lobe shows a highly suspicious (large size, ground-glass appearance, and solid morphology) part-solid nodule (arrow). (b) Follow-up image obtained 3 months after a shows progressive increase in the size of the solid component. Surgery revealed invasive adenocarcinoma. Recommendation 5: multiple subsolid lung nodules.—In patients with multiple subsolid nodules smaller than 6 mm, one must consider infectious causes. If lesions remain persistent after an initial follow-up scan at 3–6 months, consider follow-up at approximately 2 and 4 years to confirm stability, depending on the clinical setting (grade 1C; strong recommendation, low- or very-low-quality evidence). For multiple subsolid nodules, including pure ground-glass and part-solid morphologies smaller than 6 mm, short-term (3–6-month) follow-up may be appropriate when the diagnosis is uncertain and the differential diagnosis includes nonneoplastic causes. If stability is established in this time frame, follow-up examinations at 2 and 4 years are recommended to confirm absence of growth, given the likelihood of atypical adenomatous hyperplasia or adenocarcinoma in situ in such instances (34). In patients with multiple subsolid nodules with at least one nodule that is 6 mm or larger, management decisions should be based on the most suspicious nodule. In such instances, consider infectious causes. If persistent after 3–6 months, consider multiple primary adenocarcinomas (grade 1C; strong recommendation, low- or very-low-quality evidence). In patients with multiple subsolid lesions 6 mm or larger, the most suspicious nodule (which may not be the largest) should guide management (Fig 14). However, decisions regarding intervention and surgery for a dominant lesion must be constrained by the potential for other existing nodules to grow and require treatment. Also, more than one suspicious nodule increases the overall likelihood of cancer when compared with the likelihood associated with a solitary nodule. |