Stereotactic fine needle aspiration biopsy (SFNB) of breast: preliminary results in perth with the TRC mammotest machine. cytological aspects

Stereotactic fine needle aspiration biopsy (SFNB) was carried out on 404 mammographically detected impalpable breast lesions from 389 women between October 1988 and January 1990. Seventy-three lesions were excised, and 38 were carcinomas. Thirty-six of the 38 carcinomas had been diagnosed as atypical, suspicious or malignant by cytology; in the remaining 2 only fat and fibrous tissue were present in smears. The sensitivity of cyto-logical diagnosis in detecting malignancy was therefore 94.8% (36 of 38 cases). A cytological diagnosis of malignancy was made in 23 cases (5.7%) and in 5 (1.2%) the findings were suspicious of malignancy. All of these were confirmed as carcinoma histologically; the predictive value of a positive cytological diagnosis was therefore 100%. In 32 cases (7.9%) the cytological findings were atypical but inconclusive. Twenty-three of these lesions were excised, and 8 proved to be carcinoma (34.8%). No case assessed radiologically and cytologically as benign has subsequently proven to be malignant. Twenty-two of 28 cases of invasive carcinoma were given an unequivocal cytological diagnosis of malignancy; 2 were suspicious of malignancy, and in 3 the findings were atypical but inconclusive. Of the 10 pure duct carcinoma-in-situ (DCIS) lesions, (26,3% of the cancers) 1 was diagnosed cytologically as malignant, 3 as suspicious of malignancy, and 5 as atypical. The sensitivity of SFNB in detecting DCIS lesions was therefore similar to invasive carcinomas, but cases of DCIS were more likely to be given a suspicious or atypical diagnosis rather than a definite diagnosis of malignancy. The overall cytological findings were similar to those in fine needle aspiration (FNA) of palpable breast lumps, but there was a higher proportion of atypical or inconclusive reports relating to the increased proportion of DCIS lesions, smaller amounts of material and some cell trau-matization and bloodstaining of smears. The results are similar to those of other recent SFNB series and support SFNB as a useful adjunct to radiological diagnosis in the selection of mammographically detected lesions for biopsy. The role of SFNB in determining the clinical management of impalpable breast malignancy is still unclear.