The Spectrum of Sonographic Findings of Fibroadenoma of the Breast

There are a number of sonographic findings seen in fibroadenoma of the breast. In a retrospective study, we examined the biopsy results of 59 masses given the sonographic diagnosis of fibroadenoma. We also reviewed the sonograms of an additional 26 biopsy-proven fibroadenomas that were not diagnosed as such with ultrasound. The ultrasound diagnosis was correct in 50 of 76 fibroadenomas (65.8%). Only 12 of the 76 biopsy-proven fibroadenomas had the classic sonographic appearance of a smooth round or oval mass with homogeneous internal echoes. Fourteen fibroadenomas were not visible on the sonograms, even in retrospect. The remaining 50 biopsy-proven fibroadenomas demonstrated one or more "atypical" signs of border irregularity, lobulation, inhomogeneous internal echo texture, or posterior shadowing. There were nine sonographic false positives: five patients had other benign lesions on histology, and four masses believed to be sonographically compatible with fibroadenoma were found to be carcinomas. While breast sonography is frequently a useful modality for breast mass detection, particularly as an adjunct to x-ray mammography, the common overlap in characteristics of benign and malignant masses makes histologic evaluation of all solid masses essential.