Evaluation of malignancy risk in solitary pulmonary nodules

Solitary pulmonary nodule (SPN) is a common and significant clinical problem. Accurate differentiation between malignant and benign nodules not only facilitates effective treatment of early-stage lung cancer but also prevents possible unnecessary interventions for benign lesions. This study aims to identify variables predicting malignancy in patients with incidentally detected SPNs with confirmed histopathological diagnoses. A total of 229 patients were included between January 1, 2010, and June 30, 2023. Recorded variables included age, sex, smoking history, occupational risk, asbestos exposure, lung diseases, personal and family cancer history, nodule size, location, edge characteristics, density, cavitation, calcification, fat content, presence of emphysema on CT, and SUVmax values. The mean age of the patients was 61.69 ± 10.64 years, 165 of them were male. 185 patients had malignant nodules. Univariate analysis showed that advanced age (p<0.001), having lung diseases (p=0.030), nodule diameter > 2 cm (p=0.001), spiculated edge (p=0.001), lobulated edge (p=0.019), SUVmax value ≥3.96 (p<0.001), and presence of emphysema on CT (p=0.050) were significantly associated with malignant SPNs. Conversely, nodules with calcification (p<0.001), fat content (p=0.007), or connection with a fissure (p=0.011) were more likely to be benign. Multivariate regression analysis revealed that age ≥ 65 years (OR; 95% CI: 3.51; 1.31-9.45) and SUVmax value ≥ 3.96 (4.55; 1.84-11.27) were predictive of malignant SPNs, while connection with a fissure (0.10; 0.02-0.44) predicted benign SPNs. Sensitivity, specificity, positive likelihood ratio and negative likelihood ratio of the model developed to discriminate malignant SPNs were 78.3 %, 78.6 %, 3.65 and 0.28, respectively. Detection of incidental SPN in older patients and a high SUVmax value were found to be significant indicators of malignancy. SPNs associated with fissures, having a high likelihood of being benign, may be monitored with follow-up imaging. PET-CT can be performed prior to histopathologic diagnosis to rule out distant metastasis in patients with suspected malignancy, offering the possibility of simultaneous diagnosis and treatment.