Oil cyst of the breast following fat necrosis

Fat necrosis of the breast is a process of disintegration of fat cells accompanied by a foreign body reaction ending in fibrosis (Harbitz, 1935; Hadfield, 1928). Blunt trauma is considered the main aetiologic factor (Haagensen, 1971) although a history of trauma is not always available (Adair and Munzer, 1947). In some cases surgical trauma has been implicated (Haagensen, 1971; von Hoeffken and Lanyi, 1973). Pathological examination of areas of fat necrosis not infrequently reveals cystic cavities containing oily or haemorrhagic fluid. However, reports on cystic lesions containing oily material are scarce in the radiological literature. Here will be reported a case of an oil cyst revealed at mammography and treated with aspiration of the cyst content which was chemically analyzed.