Table 3.

Malignancy Rates among Solitary Circumscribed and Multiple Bilateral Circumscribed Benign-appearing Masses Seen at 6103 Screening US Examinations in 2172 Participants

Note.—Data in parentheses are raw data. Data in square brackets are 95% CIs. NA = not applicable (no entries).

^*One lesion that was initially described as clustered microcysts at the first examination was described as a complex hypoechoic mass with tiny cystic areas at 12 months and may or may not have been the same lesion, an 18-mm node-negative invasive lobular carcinoma.

^†The total with exclusion of lesions with less than 2-year follow-up and no biopsy was 0.4% (three of 836; 95% CI: 0.1%, 1.0%) for solitary lesions and 0% (zero of 127; 95% CI: 0%, 2.9%) for multiple bilateral lesions.