To investigate the predictive factors for a non-diagnostic result and the final diagnosis of pulmonary lesions with an initial non-diagnostic result on CT-guided percutaneous transthoracic needle biopsy. All percutaneous transthoracic needle biopsies performed over a 4-year period were retrospectively reviewed. The initial pathological results were classified into three categories-malignant, benign, and non-diagnostic. A non-diagnostic result was defined when no malignant cells were seen and a specific benign diagnosis could not be made. The demographic data of patients, lesions' characteristics, technique, complications, initial pathological results, and final diagnosis were reviewed. Statistical analysis was performed using binary logistic regression. Of 894 biopsies in 861 patients (male:female, 398:463; mean age 67, range 18-92 years), 690 (77.2%) were positive for malignancy, 55 (6.2%) were specific benign, and 149 (16.7%) were non-diagnostic. Of the 149 non-diagnostic biopsies, excluding 27 cases in which the final diagnosis could not be confirmed, 36% revealed malignant lesions and 64% revealed benign lesions. Predictive factors for a non-diagnostic biopsy included the size ≤ 15 mm, needle tract traversing emphysematous lung parenchyma, introducer needle outside the lesion, procedure time > 60 minutes, and presence of alveolar hemorrhage. Non-diagnostic biopsies with a history of malignancy or atypical cells on pathology were more likely to be malignant (p = 0.043 and p = 0.001). The predictive factors for a non-diagnostic biopsy were lesion size ≤ 15 mm, needle tract traversing emphysema, introducer needle outside the lesion, procedure time > 60 minutes, and presence of alveolar hemorrhage. Thirty-six percent of the non-diagnostic biopsies yielded a malignant diagnosis. In cases with a history of malignancy or the presence of atypical cells in the biopsy sample, a repeat biopsy or surgical intervention should be considered.

Teaching point: The probable mechanism of pseudoaneurysm formation related to metastatic neoplasm is a tumor embolus penetrating and destroying the vessel wall.

Objective: Pleural procedure-related tumor seeding detected by computed tomography (CT) is common in lung cancer patients with malignant pleural effusion. This study aimed to identify the incidence of tumor seeding and the associated factors among lung cancer patients with malignant pleural effusions. Material and Methods: This retrospective cohort study was conducted on 146 lung cancer patients with malignant pleural effusions, diagnosed between 2010 and 2017, who underwent at least 1 pleural procedure and had at least 2 series of CT images. The potential factors were categorized into clinical characteristics, pleural characteristics, treatment factors, and pleural procedures. Incidence rate ratios (IRR) were analyzed by Poisson regression to identify factors that were independently associated with tumor seeding. Results: The incidence of procedure-related tumor seeding was 26%. Significantly increased IRRs of tumor seeding were found in relation to 1 time (IRR 5.653, 95% confidence interval [CI] 2.549 to 12.538) and ≥2 times of conventional intercostal chest drainage (ICD) insertion (IRR 5.837, 95% CI 1.768 to 19.266), 1 time (IRR 8.924, 95% CI 3.181 to 25.033) and ≥2 times of pleural biopsy (IRR 6.485, 95% CI 1.372 to 30.660), adenocarcinoma (IRR 8.329, 95% CI 2.804 to 24.747), and pleural thickening (IRR 12.458, 95% CI 1.360 to 114.152). Conclusion: Patients who had at least one pleural biopsy or ICD insertion, pleural fluid cytology positive or suspicious for malignancy, adenocarcinoma, or pleural thickening were found to be significantly at risk for tumor seeding.