Radiographically guided fine needle aspiration cytology and core biopsy in the assessment of impalpable breast lesions

In the UK, image guided fine needle aspiration cytology (FNAC) is being used increasingly to assess impalpable breast lesions, despite limitations to the technique. This study aimed to determine whether diagnostic accuracy was improved by adding an 18 G core biopsy (CB) to radiographically guided FNAC, performed as one procedure. 169 impalpable breast lesions were biopsied by both FNAC and CB. The percentage of inadequate samples was not significantly different. For CB, the rate of false negative results was significantly higher and thus sensitivity significantly reduced compared to FNAC. CB provided extra, useful management information in 17% of cases (95% confidence intervals 11–22%). It was particularly helpful when invasive carcinoma was demonstrated, allowing definitive surgery to be planned. We conclude that when a breast cytology service is well established, addition of radiographically guided 18 G CB to the FNAC can improve the diagnostic information, but may be best used in selected rather than all cases.