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.