Sonographic Evaluation of Clinically Palpable Breast Cancers Invisible on Mammography

The purpose of this study was to determine the utility of sonography in the evaluation of palpable breast cancers invisible on mammography. A retrospective review of the pathology department's database was used to identify patients with palpable breast cancers. Consecutive patients that had excision between January 1992 and September 1997 were included. Mammograms and breast ultrasounds were reviewed retrospectively and correlated with pathologic and surgical findings. During the study period 298 women presented with a palpable breast cancer for imaging at our institution. Of these, 38 cancers (12.8%) were not seen on mammography. In 32 patients where no mammographic abnormality was found, ultrasound was able to detect a mass corresponding to the area of clinical concern. Histologic tumor types included 30 invasive ductal carcinomas, 5 ductal carcinomas in situ, and 3 invasive lobular carcinomas. Mammographic density was mild with scattered fibroglandular densities in 2 (5%), heterogeneously dense in 12 (32%), and extremely dense in 24 (63%). Thirty-one masses (97%) were hypoechoic and 1 (3%) was echogenic. Lesion margins were irregular in 23 (72%), lobulated in 5 (16%), and well-circumscribed in 4 (12%). In this group of patients the combination of mammography and ultrasound of the mass demonstrated 99% of the palpable cancers. In patients presenting with a breast mass on physical examination in whom mammography fails to demonstrate an abnormality, supplemental ultrasound is helpful in most instances to further characterize the lesion.