E1592. What’s a Little Fat Between Friends? A Review of Fat Necrosis in the Breast
  1. Ariel Fisher; University of Rochester Medical Center
  2. Berney Vincent; University of Rochester Medical Center
  3. Avice O'Connell; University of Rochester Medical Center
  4. David Hicks; University of Rochester Medical Center
Fat Necrosis (FN) is one of the most common findings in breast imaging. It can be caused by virtually any insult to the breast including trauma, surgery, and radiation. Even to the experienced Breast Imager, FN can present a diagnostic dilemma, to biopsy, offer short-term follow-up or recommend a return to annual screening? FN can take on many bizarre appearances including developing asymmetries all the way through to frank spiculated masses. Having a firm understanding of what to look for and how to appropriately assign a Breast Imaging-Reporting and Data System (BIRADS) designation will reduce unnecessary biopsies and prevent our patients from experiencing undue anxiety. Biopsies are based on the presence of the most worrisome features across multiple modalities and it may be impossible to not biopsy a finding that turns out to be FN. It is those cases in which a safe and accurate benign BIRADS designation can be assigned that we want to work towards avoiding a biopsy. The cases where we can say with a high degree of confidence; this is most likely benign FN, BIRADS 2. Following the rules laid out in BIRADS v5 has provided Breast Imagers an effective framework to do so.

Educational Goals / Teaching Points
To review all characteristic imaging findings associated with FN across 3 imaging modalities: Digital Breast Imaging/Tomosynthesis (DBI), Ultrasound (US) and Magnetic Resonance Imaging (MRI). Through a series of cases, we will see how to use BIRADS descriptors and see several different examples of each feature. For example, we will see how the architectural distortion caused by a focus of fat necrosis can be appreciated across all 3 modalities. We will provide practical, tried and true advice from our institution’s exceptional career-long breast imagers. We will examine the three stages of fat necrosis from a histological standpoint with comparison to the imaging features to better understand the natural history of this common physiological phenomenon.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Fat Necrosis features on DBI and US we will examine include calcification, architectural distortions, franks masses of various densities, evolution over time and the decision to biopsy or not and the result. MRI of breasts will show us some features of fat necrosis that are pathognomonic and do not require further imaging including the well named “black hole sign.”

The only way to understand fat necrosis is to have seen it in all its various forms. Necessary biopsies are unavoidable, but we can reduce the number of unnecessary biopsies by appreciating the basic imaging features discussed, using prior imaging and honest discussion with ourselves and our patients.