Pancreas head carcinoma with total fat replacement of the dorsal exocrine pancreas

We report a case of pancreas head carcinoma associated with fat replacement of the body and tail. A 68-year-old man presented with obstructive jaundice and was admitted to our hospital. Ultrasonography and computed tomography showed pancreas head tumor with a neighboring cystic lesion and fatty replacement of parenchyma of the pancreas body and tail. By endoscopic retrograde pancreatography, abruption of the main pancreatic duct and the presence of an accessory duct were detected. After percutaneous transhepatic biliary drainage, pancreatoduodenectomy was successfully performed. At laparotomy, the pancreas head was easily dissected from the replaced fatty tissue of the body and tail without continuity of the ductal system or parenchyma. Microscopic examination revealed the existence of an infiltrating ductal adenocarcinoma and a neighboring. cyst in the pancreas head. The dorsal exocrine pancreas was completely replaced by the fat tissues, in which viable Langerhans' islets were scattered. The patient's postoperative course was uneventful, and exogenous insulin administration was unnecessary for the maintenance of normal blood sugar level. Acquired fat replacement of the body and tail of the pancreas is an uncommon disorder, mimicking congenital agenesis of the dorsal pancreas. Though the mechanism is controversial, obstruction of the main pancreatic duct by a cystic lesion or carcinoma in the pancreas head is a possible cause of fatty degeneration of the pancreatic parenchyma.