Band-like interposing fat along large vessels: Ultrasonographic pseudolesions of the breast

Objective: The aim of this study is to evaluate the clinical characteristics and ultrasonographic findings of band-like interposing fat as well as to identify additional approaches for its diagnosis. Materials and Methods: This study included 26 confirmed cases of band-like interposing fat from June 2008 to June 2010. A retrospective analysis was performed to evaluate the clinical characteristics and ultrasonographic findings in these cases. Five radiologists analyzed the ultrasonographic findings, which correlated with the mammographic and MRI findings when available, according to Breast Imaging Reporting and Data System classification. Results: None of the 26 patients had any symptoms. In 92.3% of the patients, the lesion was located in the upper outer quadrant of the breast. The mean distance of the lesion from the nipple was 2.4 ± 0.7 cm (1.1-4.5). The mean depth of the lesion from the skin was 1.3 ± 0.3 cm (0.8-2.1). The mean maximal length of the lesion was 0.8 ± 0.4 cm (0.3-1.8). The following were the most frequent ultrasonographic findings of lesions: irregular shape, not parallel orientation, indistinct margins, abrupt interface, hypoechogenicity, no posterior feature, no calcification, and presence of vascularity. The most frequent BI-RADS category was 4a. There were no suspicious findings on the mammography or MRI. Conclusion: Ultrasonographic findings may lead to misclassification of band-like interposing fat as a malignancy. A better understanding of the clinical and ultrasonographic characteristics of band-like interposing fat would facilitate its differentiation from a true mass.