The value of routine cytologic examination of breast cyst fluids.

The results of the cytologic examination of 6,782 consecutive breast cyst fluids aspirated from 4,105 women during the period 1976 to 1983 were reviewed to assess the value of the routine cytologic study of such specimens. Cases in which cancer had been suspected by physical examination and/or mammography before aspiration of the cyst were excluded from the evaluation. Five clinically and radiologically inapparent intracystic papillomas were detected overall (0.1%). All cases of intracystic papilloma produced a blood-stained fluid and showed an intracystic mass at pneumocystography. Cytology was negative in two of these cases and falsely positive in one case while correctly identifying the papilloma in two cases. One incidental case of occult in situ lobular carcinoma was also detected. Routine cytologic examination of all breast fluids is thus not recommended as a cost-effective practice. Cytology should be used only when a blood-stained fluid is obtained (2% in the present series) since its indiscriminate application to all cyst fluids does not affect the rate of detection of intracystic lesions, most of which are suspected before the aspiration.