Fat necrosis is the rupture of fat cells, either due to endogenous factors or as a result of trauma, and is a type of liquefactive necrosis. The breast is composed of a large amount of fat and glands, and when the breast tissue is traumatized, resulting in the rupture of fat cells within the breast, localized fat necrosis can easily develop, leading to the painful formation of a tumor-like mass. Also more commonly in acute pancreatitis, as the pancreas becomes swollen and congested, there is a large amount of fluid, especially when the pancreatic ducts that secrete pancreatic fluid are obstructed by exogenous factors, the pancreatic fluid from the pancreas secretes people’s own fat. In particular, the fat in the greater omentum of the abdominal cavity causes lipolysis into fatty acids and calcium ions, which combine to form a grayish-white calcification visible to the naked eye called saponified plaque, also known as fatty acid calcium, which would be the residual aftermath of fat necrosis.