Mobile encapsulated adipose tissue (MEAT) of cows and humans: a distinct nonneoplastic entity.

Mobile encapsulated adipose tissue can be found in both the subcutis and peritoneal cavity. The cutaneous lesions are more common and better described; they are usually designated as "mobile encapsulated lipoma" or "nodular-cystic fat necrosis." The clinical name of abacus tumor describes best the small marble-like nodules that often can be moved freely through the subcutaneous tissue planes. Histopathologically, the nodules are composed of a dense fibrous capsule surrounding fat that may show varying degrees of necrosis, calcification, and lipomembranous changes. The peritoneal nodules are thought to originate from detached epiploic appendices. They are described occasionally in humans but more commonly in cows. Because these bovine mobile peritoneal bodies are clinically and histopathologically identical to the nodules in human subcutaneous tissue, the authors suggest that one can better understand both processes by comparing them. Because the lesions are reactive, not neoplastic, and necrosis is not an invariable feature, the authors suggest the neutral designation of mobile encapsulated adipose tissue.