Non-specific benign pathological results on transthoracic core-needle biopsy: how to differentiate false-negatives?

OBJECTIVES: To determine the negative predictive value (NPV) of non-specific benign results from cone-beam CT (CBCT)-guided transthoracic core-needle biopsy (TTNB) and identify predicting factors for false-negative for malignancies.

METHODS: From January 2009-December 2011, 1,108 consecutive patients with 1,116 lung lesions underwent CBCT-guided TTNB using an 18-gauge coaxial cutting needle. Among them, 226 patients with 226 TTNBs, initially diagnosed as non-specific benign, were included in this study. The medical charts, radiological or pathological follow-ups were reviewed to classify false-negative and true-negative results and to identify which variables were associated with false-negatives.

RESULTS: Of 226 lesions, 24 (10.6%) were finally confirmed as malignancies and 202 (89.4%) as benign, of which the NPV was 89.4% (202/226). Multivariate analysis revealed that part-solid nodule (PSN) (odds ratio (OR), 3.95; P = 0.022), a biopsy result of 'granulomatous inflammation' (OR, 0.04; P = 0.022), and exact location of needle tip within targets (OR, 0.37; P = 0.045) were significantly associated with false-negatives among initial non-specific benign biopsy results.

CONCLUSION: The NPV of the non-specific benign biopsy was 89.4%. PSN was a significant positive indicator, but a biopsy result of 'granulomatous inflammation' and exact location of needle tip within targets were significant negative indicators for false-negatives.

KEY POINTS: • The negative predictive value of the non-specific benign biopsy was 89.4%. • A part-solid nodule is a significant predictor for false-negative biopsy (OR = 3.95). • Pathological diagnosis of granulomatous inflammation is a robust indicator for 'true-negatives'. • Identifying needle tip within target lesions is a significant predictor for 'true-negatives'.