OBJECTIVETo study the basic morphological factors and the reliability and limitations of the diagnostic standards of fine needle aspiration cytology (FNAC) of breast masses which drafted.

METHODSA total of 4 309 fine needle aspiration biopsy cases of breast were performed and 951 cases of which were checked with their histological diagnosis.

RESULTSOf the 413 aspiration smear studies, relatively identical morphological features were found on the smears of lesions of the same nature. The sensitivity of diagnosis of malignant tumor in 732 cases, the specificity of diagnosis of benign lesion in 219 cases and the overall accuracy of diagnosis were 97.3%, 97.7%, and 97.4% respectively. The false negative rate, potential false positive rate and the overall misdiagnosis rate were 2.7%, 2.3% and 2.6% respectively, no false positive diagnosis case was found.

CONCLUSIONS(1) The differentiation and the arrangement pattern of the tubular epithelial cells and the amount of benign naked nuclear cells are the three essential factors in the analysis of morphological changes of FNAC of breast mass. (2) The examination of our diagnostic standards of FNAC of breast masses shows that the standards are very reliable but have certain limitations which need to be resolved by histopathological diagnosis.