Ultrasound-guided fine-needle aspiration biopsy remains a valid approach in the evaluation of nonpalpable breast lesions.

The use of ultrasound-guided fine-needle aspiration (FNA) biopsy for nonpalpable breast lesions varies considerably. This retrospective study stresses the role of breast FNA in evaluating sonographically suspicious nonpalpable breast masses using a probabilistic reporting system. One hundred and eight consecutive ultrasound-guided FNA biopsies diagnosed as positive (32), suspicious (8), atypical (11), benign (55), and unsatisfactory (2) were analyzed and correlated with 61 subsequent surgical specimens. All positive cytologies showed carcinoma on histology; suspicious cases were followed by 5 carcinomas, 2 fibroadenomas, and 1 papillary lesion. Follow-up of atypical cases included 4 carcinomas, 3 fibroadenomas, and 2 papillary lesions, while all 10 biopsies following benign cytology showed fibrocystic changes. Two cases with suspicious sonographic findings but unsatisfactory cytology had lobular carcinoma. The remainder of the benign and atypical cases were followed clinically and radiographically for at least 10 months and had no evidence of carcinoma. Positive predictive values were positive, 100%; suspicious, 63%; atypical, 36%; benign, 0%. Most (40/43; 93%) carcinomas were invasive. In conclusion, ultrasound-guided FNA for nonpalpable breast lesions is highly accurate, and probabilistic reporting helps direct patient management.