Fat necrosis has been found to be associated with many forms of pancreatitis, carcinoma of the pancreas and pancreatic trauma. The causative agents seem to be pancreatic lipase and colipase, which presumably escape from the pancreas during the development of the disease. The precise mechanism by which these factors attack the adipose tissue, leading to the formation of foci of fat necrosis, is not known. The pathologic finding of fat necrosis is not restricted to the peritoneal-retroperitoneal region, where a direct contact with these factors is the most likely cause. In other patients, fat necrosis involves peripheral tissues, notably in subcutaneous adipose tissue throughout the body, in joints of the hand and foot and in bone marrow. This is associated with additional complications dependent upon the sites involved and is manifested as skin lesions, polyarthritis and osteolytic defects in patients who sometime suffer from a primary pancreatic disease.