Pancreatic Lipomatosis: An Extensive Pictorial Review.

Pancreatic lipomatosis - also commonly called fat replacement - represents the most frequent benign pathologic condition of the adult pancreas. Most cases remain asymptomatic, and only some rare extreme degrees of lipomatosis or fat replacement may lead to exocrine pancreatic insufficiency. The precise etiology of the entity remains unclear, and the condition has been found associated with several diseases comprising diabetes mellitus, metabolic syndrome, acquired or hereditary pancreatitis, alcoholic hepatitis, cystic fibrosis and condition comprising increasing age, body mass index, or more precisely visceral fat index, and use of steroid therapy. Numerous cases are also associated with condition compromising the permeability of the pancreas ductal system, such as intraductal calculus, pancreatic tumors, and congenital or experimental stenosis. Uneven lipomatosis and fat replacement are also common presentations and responsible for the great diversity of imaging features. The reasons for uneven presentations are controversial and probably interweave embryologic or ductal hypotheses. Lipomatous pseudohypertrophy of the pancreas represents the most extreme situation of pancreatic lipomatosis and is considered, probably in a contestable way, as a rare, specific, and distinct entity. We hereby present an extensive pictorial review of the broad spectrum of imaging features of this entity. The images are extracted from a compilation of cases collected in our department over more than a decade. We review and discuss the embryologic and ductal hypothesis, the differential diagnosis. Finally, we illustrate some unusual presentations and evolutions.