Likelihood of malignancy in breast lesions characterised by ultrasound with a combined diagnostic score.

To determine the positive predictive value of breast ultrasound (US) categories and US features, isolated and in combination, 398 consecutive sonographically diagnosed breast tumours with histologic or cytologic diagnosis were reviewed. Tumour characterisation and the sonographer's diagnoses were recorded prospectively using the diagnostic classification of the European Society of Mastology (EUSOMA) (U2 = probably benign lesion, U3 = an abnormality present of indeterminate significance, U4 = features suspicious of malignancy). In addition, based on the likelihood of malignancy of each US characteristic, a diagnostic score was developed. These two measures were compared. US-guided biopsy revealed 338 benign and 60 (55 invasive and 5 noninvasive) malignant lesions. EUSOMA and diagnostic score classifications did not differ significantly. If all breast tumours classified U3 and U4 were to be tested, every second biopsy (48.3%) would have revealed a carcinoma with a negative predictive value of 99.3%. The frequency of carcinoma in sonographically benign lesions (U2 or score 1) was 0.7 and 2.2%, respectively, an incidence similar to that with mammographic lesions classified as BI-RADS 3 (Breast Imaging Reporting and Data System, probably benign, short interval follow-up suggested). Thus, given that clinical symptoms and real-time imaging influence the sonographer's interpretation, the proposed diagnostic score can improve the diagnostic accuracy of the breast sonogram with the result of reducing invasive testing and maintaining a high detection rate.