Non-Nodular CT Patterns of Solid Lung Cancer in the Early Growth Phase: A Two-Center Retrospective Study

Background/Objectives: Early diagnosis of solid lung cancer (SLC) is essential for better prognosis. However, non-nodular patterns, atypical CT manifestations of SLC in the early growth phase, are easily overlooked, potentially leading to delayed diagnosis. This study aimed to characterize the clinical features and CT findings of non-nodular patterns of SLC in the early growth phase. Methods: Between January 2015 and October 2025, 365 patients with 365 pathologically confirmed SLCs were retrospectively enrolled from two centers. Based on initial morphological appearances, lesions were classified into nodular and non-nodular groups (patch-like, strip-like, bead-like, pleural plaque-like, and cystic-cavity subtypes). Clinical data and CT findings were summarized and compared between the two groups. Results: Of the 365 SLCs, 107 (29.32%) initially presented as non-nodular lesions, among which patch-like lesions (56, 52.34%) were the most prevalent, followed by bead-like (20, 18.69%), strip-like (16, 14.95%), pleural plaque-like (9, 8.41%), and cystic-cavity lesions (6, 5.61%). Both nodular and non-nodular lesions were predominantly located in the upper lobes (55.04% vs. 58.88%, p = 0.611). Multivariable analysis revealed that smoking history (adjusted odds ratio [aOR], 2.93; 95% confidence interval [CI], 1.05-8.28; p = 0.040), subpleural distribution (aOR, 3.37; 95% CI, 1.61-7.72; p < 0.001), interstitial lung disease (ILD) (aOR, 66.45; 95% CI, 23.57-220.04; p < 0.001), and post-tuberculosis lung changes (aOR, 8.60; 95% CI, 2.37-32.64; p = 0.001) were independently associated with a non-nodular pattern (AUC: 0.869; p < 0.001). Conclusions: In smokers or patients with ILD/post-tuberculosis lung changes, subpleural non-nodular lesions in the upper lobes require close monitoring for growth.