Incidental findings on sonography of the breast: Clinical significance anddiagnostic workup

OBJECTIVE. The purpose of this study was to determine how often physician-p erformed high-resolution sonography can detect nonpalpable breast lesions n ot revealed by mammography. A sonographic classification scheme was tested for its accuracy in predicting malignancy of incidentally detected breast l esions. SUBJECTS AND METHODS, Six thousand one hundred thirteen asymptomatic women with breast density grades 2-4 and 687 patients with palpable or mammograph ically detected breast masses underwent sonography as an adjunct to mammogr aphy. All sonographically detected, clinically and mammographically occult breast lesions that were not simple cysts were prospectively classified int o benign, indeterminate, or malignant categories. Diagnoses were confirmed by sonographically guided fine-needle aspiration or core needle biopsy. RESULTS. In 6113 asymptomatic women, 23 malignancies in 21 patients were de tected with sonography only (prevalence, 0.31%). Five additional malignant lesions were found in patients with a malignant (n = 3) or a benign (n = 2) palpable or mammographically detected index lesion. The mean size of invas ive malignancies detected only by sonography was 9.1 mm, which was not sign ificantly different from the mean size of invasive cancers detected by mamm ography (p = .07). The sensitivity of the prospective sonographic classific ation for malignancy was 100%, and the specificity was 33.5%. CONCLUSION. The use of high-resolution sonography as an adjunct to mammogra phy in women, with dense breasts may lead to detection of a significant num ber of otherwise occult malignancies that are no different in size from non palpable mammographically detected lesions. Prospective classification of t hese lesions based on sonographic characteristics results in a significant reduction in number of unnecessary biopsies performed.