Ultrasonographic hyperechoic lesions of the breast: are they always benign?

Background: Most of the breast lesions show hypoechogenicity relative to fat on ultrasonography. The frequency and malignancy rate of hyperechoic lesions are not investigated in a large series.

Purpose: To evaluate the frequency and malignancy rate of hyperechoic lesions on breast sonography and to investigate sonographic characteristics that may predict malignancy in hyperechoic breast lesions.

Material and methods: Radiologic reports of 16,416 patients who underwent breast sonography between 2007 and 2008 were searched using "hyperechoic", "echogenic" or "heterogeneous echoic" to describe lesions. Sonographic findings were evaluated according to the Breast Imaging Reporting and Data System lexicon. Clinical records including follow-up and pathologic findings were also reviewed. We calculated the frequency of hyperechoic lesions and their malignancy rate. Differences in sonographic appearances between benign and malignant lesions were also investigated.

Results: Among the 16,416 patients, 103 (0.6%) hyperechoic lesions were identified (mean size, 1.79 cm). Of these 103 lesions, 27 (26.2%) were pathologically evaluated and five (4.9%, 4 invasive ductal carcinoma and 1 mucinous carcinoma) were confirmed as malignant. Among the 819 malignant lesions diagnosed using sonography-guided core needle biopsy, five (0.6%) were hyperechoic. In benign lesions, fat necrosis and fibroadenoma were common pathologic diagnoses. Malignant lesions were more likely to have irregular shape (P = 0.003), non-parallel orientation (P = 0.002), non-circumscribed margin (P = 0.007), and a hypoechoic area (P = 0.027) than benign lesions. All hyperechoic carcinomas were seen as suspicious masses on mammograms.

Conclusion: Hyperechoic masses are very rare and mostly benign. As an adjunct to mammography, the imaging findings reported here could help to avoid misdiagnosis for malignant hyperechoic lesion.