Stereotactic aspiration biopsy of nonpalpable nodules of the breast

To evaluate the reliability of stereotactic aspiration biopsy (SAB) in assessing which nonpalpable nodules of the breast should be excised, SAB was performed upon 373 nodules. The nodules were classified as well-circumscribed or irregular and evaluated for the presence of microcalcifications. The cytologic diagnoses were classified as malignant, atypical or benign. Cytologically malignant and atypical nodules were excised. Benign nodules were excised if there was a family or past history of carcinoma of the breast or if they changed mammographically. Twenty-five nodules proved to be malignant. Of these, the diagnoses by stereotactic aspiration biopsy were adenocarcinoma in 20 patients, atypical in three, malignant hemangiopericytoma in one patient and benign in one. The borders of the malignant nodules were well-defined in eight patients and irregular in 17. Three malignant nodules with irregular borders had clustered microcalcifications. One false-positive instance was a sclerosing papilloma with atypical hyperplasia. Twenty-four nodules with benign cytologic diagnoses, which were excised, proved to be benign. An additional 132 nodules with benign cytologic diagnoses had six month interval mammograms for two years; 131 were without interval change and one increased in size and proved to be a carcinoma. SAB is reliable for diagnosing nonpalpable nodules. Nodules with malignant and atypical results must be excised. It is reasonable to have follow-up evaluation of well-defined nodules mammographically when the aspirate is benign.