Atypical Sonographic Patterns of Fibroadenoma of the Breast: Pathologic Correlation

PURPOSE: To correlate the atypical sonographic patterns of fibroadenoma of the breast with the pathologicfindings. MATERIALS AND METHODS: Among 203 surgically proven 43 which were sonographi-cally atypicalfibroadenomas, were retrospectively reviewed. The diagnostic criteria for atypical va riety, as seen onsonography, were an ill-defined margin, microlobulated or irregular shape, heterogeneous internal echo-pattern,posterior shadowing, micro-calcification, and clefts. The atypical sonographic patterns of these 43 fibroadenomaswere analysed and compared with the pathologic findings. RESULTS: Among 43 lesions, ill-defined margins orirregular shapes were seen in 15 c a s e s, heterogeneous internal echo-patterns in 27, posterior attenuation innine, and clefts in seven. Thirty-seven (86%) of the 43 were predominantly ductal or hada mixed ductal and stromalcomponent. Eleven (73.3%) of fifteen ill-defined margin or irregular shaped lesions were caused by interdigitationof surrounding normal breast parenchyma and mass. Twenty two (81.5%) of 27 heterogeneous internal echo-pat-ternswere related to dilated ducts, phyllodes features, collagen bundles, adenosis, mi-crocalcification, or fatvacuoles. Eight (88.9%) of nine posterior attenuations were caused by collagen bundles, microcalcification, ductalproliferation or dilatation. All seven cases showing clefts revealed phyllodes features and dilated ducts. CONCLUSIONS: Most atypical fibroadenomas had a redominantly ductal or mixed component. Ill-defined margin orirregular shape was mainly due to interdigitation of normal surrounding parenchyma. Variable histologic featureswere related to the het-erogeneous internal echo-pattern, posterior shadowing, and the clefts revealed by atypicalsonographic findings.