Teaching Case 27

52 y/o F with recalled from screening for a left asymmetry. What is the most likely diagnosis?

Fat Necrosis

  • Saponification of local fat – benign inflammatory process
  • Related to direct trauma or surgery
  • Middle-aged women with pendulous breasts are more prone
  • Can evolve into an oil cyst (fine curvilinear calcification of the wall)
  • Mammo: Fat density [focal] asymmetry
  • US: Variable
    • Acute – hyperechoic due to edema
    • Subacute – ill-defined cystic lesion (anechoic) surrounded by edema (hyperechoic)
    • Late – round/oval mass with shadowing calcified walls

Related Radiology Article: Taboada JL, Stephens TW, Krishnamurthy S, Brandt KR, Whitman GJ. The many faces of fat necrosis in the breast. AJR Am J Roentgenol. 2009 Mar 1;192(3):815-25.