Conclusiveness of fine needle aspiration in 2419 histologically confirmed benign and malignant breast lesions.

We aimed to retrospectively assess (1) the conclusiveness of breast fine needle aspiration (FNA) in a histologically confirmed population and (2) the clinical and radiologic determinants of a conclusive diagnosis. Aspirates were diagnosed as inadequate, benign, atypical, suspicious or malignant. We defined a conclusive FNA diagnosis as 'benign' in histologically benign lesions and as 'malignant' in histologically malignant lesions. In 2419 breast lesions, the proportion of conclusive diagnoses was 46.1% (95% confidence interval, 42.0-50.2%) in histologically benign lesions (n = 571) and 81.6% (95% confidence interval, 79.8%-83.4%) in histologically malignant lesions (n = 1848). On multivariate analysis, factors associated with a conclusive preoperative diagnosis included tumour diameter of 2-2.9 cm (P < 0.001), malignant histology (P < 0.001) and the pathologist examining the aspirate (P = 0.02). Breast FNA has to be utilised selectively in the routine work-up of breast lesions. In suspicious lesions of large size, FNA may still be used to obtain a quick confirmation of malignancy.