CT-guided coaxial biopsy of malignant lung lesions: Are cores from 20-gauge needle adequate for histologic diagnosis and molecular analysis?

Background: To determine the number of cores adequate for histopathologic diagnosis as well as evaluate the success rate of molecular analyses in CT-guided percutaneous core needle biopsy (PCNB) for malignant pulmonary lesions using a 20-guage coaxial needle. Methods: Biopsy records of 196 malignant lung lesions were reviewed. Core obtained from each needle pass was put in a separate container for individual pathological analysis. Types of molecular analysis attempted and their success rates were recorded for each patient. We categorized each patient into one of six groups according to the number of cores (n=1, n=2, n=3, n=4, n=5, n≥6) acquired, and diagnostic sensitivity for histopathologic diagnosis was calculated for each core in each group. In order to assess the increase in cumulative sensitivity up to 4th core, the data from 1st to 4th needle passes in 4-, 5-, and ≥6-core groups were pooled and cumulative diagnostic sensitivities up to 4th core were calculated. Results: Of 196 cases of lung malignancies, five different types of molecular studies (EGFR mutation, ALK translocation, KRAS mutation, RET and ROS1 rearrangements) were attempted with PCNB specimens in 100 cases and successfully done in 96 cases (96.0%). In ≥4-core group (4-, 5-, and ≥6-core groups combined; n=148), cumulative sensitivity increased from 83.8% to 89.9% between 1st and 2nd cores, 89.9% to 93.2% between 2nd and 3rd cores, and 93.2% to 94.6% between 3rd and 4th cores. Conclusions: The cumulative diagnostic sensitivity for the histopathologic diagnosis increases significantly between the second and fourth sampling. Multiple samples obtained with a 20-guage coaxial needle are adequate and have a high success rate for various molecular studies for lung malignancy.