Diagnostic utility and limitations of CT-guided transthoracic fine-needle aspiration biopsy in Lung-RADS 4 pulmonary nodules ≤2 cm

BACKGROUND: Managing small Lung-RADS 4 pulmonary nodules is clinically challenging. While CT-guided TTFNAB is standard, its efficacy and safety for lesions ≤2 cm require further evaluation to optimize outcomes and reduce unnecessary surgeries. OBJECTIVES: This study aimed to evaluate the diagnostic accuracy, safety, and factors influencing the outcomes of CT-guided TTFNAB in Lung-RADS category 4 pulmonary nodules measuring ≤2 cm. DESIGN: Retrospective study SETTING: Single-center, a tertiary referral center MATERIALS AND METHODS: A retrospective analysis was performed on 95 patients who underwent CT-guided TTFNAB between January 2021 and April 2024. Data included demographics, lesion characteristics (size, location, density, and pleural proximity), histopathological findings, and procedural outcomes. MAIN OUTCOME MEASURES: The primary endpoints were diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and factors influencing TTFNAB results, alongside procedural complications—specifically pneumothorax and chest tube requirement. SAMPLE SIZE: 95 patients RESULTS: Of the 95 nodules, 26 (27%) were benign and 69 (73%) were malignant according to TTFNAB. Final pathology confirmed 18 (19%) benign and 77 (81%) malignant lesions. All biopsies yielded sufficient material. Sensitivity, specificity, and overall diagnostic accuracy were 83%, 94%, and 89%, respectively. The PPV was 98%, while the NPV was 65%. Pleural thickening was significantly more frequent in both the TTFNAB benign group (38% vs. 13%, P =.006) and final benign diagnosis group (44% vs. 14%, P =.008). Pneumothorax occurred in 30% of cases, with 24% of these requiring chest tube drainage. No significant associations were found between diagnostic accuracy or complications and variables such as age, emphysema, Lung-RADS category, or nodule size. CONCLUSION: CT-guided TTFNAB is an effective diagnostic method for confirming malignancy in pulmonary nodules ≤2 cm classified as Lung-RADS 4, providing an overall accuracy of 89% and a PPV of 98%. However, a benign TTFNAB result cannot be considered diagnostically safe: the NPV of 65% and false-negative rate of 35% indicate that a negative biopsy does not reliably exclude malignancy. Clinicians must not rely on a negative result alone; close radiological follow-up or surgical biopsy is essential for these high-risk lesions. LIMITATIONS: The retrospective single-center design, small sample size, and limited generalizability. IRB APPROVAL NUMBER: 2024/010.99/6/23 (Date: 26.07.2024)