Fat necrosis in the breast: sonographic features

To evaluate the ultrasonographic (US) features and evolution of fat necrosis in the breast.

The US features of 31 breast masses in 23 patients were reviewed. Fat necrosis was diagnosed on the basis of histologic (n = 20) and initial or follow-up (minimum follow-up, 15 months) mammographic (n = 11) findings.

Sonograms demonstrated discrete masses in all but one patient. On the basis of the predominant US finding, masses were categorized as solid (n = 15), complex with mural nodules (n = 7), complex with echogenic bands (n = 4), anechoic with posterior acoustic enhancement (n = 2), anechoic with shadowing (n = 2), or no mass visible (n = 1). Distortion of the normal parenchymal architecture was seen in 21 masses. In four six masses, 1-26-month follow-up sonograms showed evolution of the US appearance. One solid mass remained solid appearing. Complex masses tended to evolve: Three became more solid appearing, and one became more cystic. No mass enlarged; two remained stable, and four decreased in size.

A spectrum of US findings is associated with fat necrosis. If fat necrosis is suspected and mammographic findings are suspicious, knowledge of the US appearance and evolution of these patterns may enable imaging follow-up of these lesions rather than needless biopsy.