CT-guided thoracic core biopsies: value of a negative result

Previous studies have reported low negative predictive values (NPV) for computed tomography (CT)-guided fine needle aspiration of lung nodules in excluding malignancy. Our aim was to determine the NPV of transthoracic core needle biopsy in a tertiary care hospital with a large cancer patient population. The results of 226 consecutive CT-guided transthoracic core needle biopsies were reviewed. Results were classified into one of the following four groups: positive or suspicious for malignancy, benign specific, benign non-specific, and non-diagnostic. The benign specific group included entities such as fungus, hamartoma and schwannoma. In the benign non-specific group, histologic findings such as scar and inflammation were reported. The non-diagnostic group included cases with only normal pulmonary tissue in the specimen and/or insufficient tissue to render any diagnosis. The results were correlated with subsequent proof obtained via surgery or clinical and imaging follow-up. Out of a total of 226 biopsies, 158 were positive or suspicious for malignancy, 8 were benign specific, 32 were benign non-specific and 28 were non-diagnostic. Forty-three benign non-specific or non-diagnostic cases had subsequent proof, and malignancy was subsequently confirmed in 16/43 cases (5/21 non-specific and 11/22 non-diagnostic cases). The NPVs were 76% and 50% for benign non-specific and non-diagnostic biopsies, respectively. The overall NPV and false negative rate were 68% and 9%, respectively. A core biopsy revealing non-specific benign tissue or insufficient tissue for diagnosis is unreliable in excluding malignancy, and patients with these types of biopsy results should have resampling of tissue or close clinical and imaging follow-up.