Abstract No. 566 Utility of Percutaneous Lung Nodule Biopsy in Patients with Known Non-Lung Primary Malignancy

Percutaneous image-guided lung biopsy is a common diagnostic procedure that entails unique risks for the patient. While imaging can be suggestive of metastatic lung disease in patients with known non-lung primary malignancy, a biopsy is frequently ordered for confirmation and further testing. The purpose of the study is to evaluate utility of lung nodule biopsy in patients with known extra-pulmonary malignancy and to determine if imaging appearance of the lung nodule has predictive value. Retrospective analysis of 1638 percutaneous lung biopsies was performed from 8/2018 through 9/2021 in a tertiary cancer center. Patients with primary lung malignancy, no known malignancy, or biopsies performed for research were excluded. 1057 lung biopsies in 1007 patients were included in the study. Medical records and imaging were reviewed for histology, biopsy site, number, size and imaging characteristics of lung nodules, as well as technical success of the biopsies. Chi-square analysis was performed to compare variables. There were 898 (85%) patients with pre-existing non-hematologic malignancy, 100 (9.5%) patients with hematologic malignancies, and 13 (1.2%) patients with both. 91% were solid nodules, 55% of patients had multiple nodules. Median tumor size was 2.2 cm (range, 0.6-18.7 cm). 39% of patients were found to have a different histology on lung biopsy when compared with pre-existing diagnosis. Different histology was more commonly found in hematologic malignancies (56% vs 34.7%, P< 0.001). The diagnosis was more frequently different in patients with a single lung nodule when compared with multiple pre-existing nodules (61% vs 39%, P< 0.001). Tumor size did not have predictive value (P = 0.4). While imaging characteristics can be suggestive of metastatic lung disease, it cannot be considered diagnostic as 34.7% of the patients were diagnosed with a second malignancy. Different pathology is more frequently found in hematologic malignancies and in patients with a single lung nodule at time of biopsy.