Teaching Case

A 50-year-old woman presented at the Emergency Department with a history of general sickness, epigastric pain radiating to the back associated with nausea and vomiting. She did not have risk factors for cardiovascular diseases.

An abdominopelvic CT was performed to rule out acute aortic pathology. CT showed no pancreatic parenchyma. It was totally replaced by fatty tissue with an attenuation value of - 115 HU. An MRI study confirmed the diagnosis by showing the pancreaticobiliary duct system. There was no dilatation of intrahepatic biliary radicals, common bile duct or intrapancreatic ducts. Neither pancreatic mass nor calcification were seen.

Pancreatic lipomatosis refers to fatty replacement of the normal pancreatic gland and can be partial or complete [3]. It is also known as fatty infiltration, fatty replacement of exocrine pancreas, lipomatous pseudo-hypertrophy of the pancreas or pancreatic steatosis [4, 5, 7]. The aetiopathogenesis of pancreatic lipomatosis still remains unknown [2]. It tends to be associated with elderly age, obesity, diabetes, steroid therapy, Cushing disease, pancreatitis, haemachromatosis, malnutrition or congenital abnormalities such as cystic fibrosis or Schwachman - Diamond syndrome [1, 3, 5, 6].

Patients with pancreatic lipomatosis could be asymptomatic or present atypical abdominal pain or steatorrhea. Clinical symptoms depend on the fatty replacement degree [1].

Focal lipomatosis is a common disorder without clinical significance. This condition may simulate a mass-like lesion. The fatty replacement may be heterogeneous, therefore four different types of uneven pancreatic lipomatosis have been described [6]:
Type - 1A characterized by fatty replacement of the head.
Type - 1B characterized by fatty replacement of the head, neck and body.
Type - 2A characterized by fatty replacement of the head and uncinate process.
Type - 2B characterized by near total replacement of the pancreas except the peribiliary region.

Nevertheless the complete pancreatic lipomatosis is a rare entity and could be associated with congenital syndromes or obstruction of the pancreatic duct. In addition, an extreme degree of fatty infiltration may produce a severe exocrine pancreatic insufficiency.

Abdominal ultrasound shows a hyperechogenic pancreas that is hardly discernible from the surrounding tissue. CT and MRI are especially helpful in the evaluation of pancreatic lipomatosis and also in detecting aetiologies such as obstructive calculi or neoplasms [5]. Both techniques reveal that pancreatic parenchyma is replaced with abundant fat tissue and may not be identifiable [3]. The presence of the Wirsung conduct is the key for the diagnosis, so MRI cholangiography sequences are essential [3, 6].

Differential diagnosis of complete lipomatosis includes agenesia of the dorsal pancreas. However, in case of agenesia of the dorsal pancreas, the neck, body and tail of the pancreas, the duct of Santorini and the minor duodenal papilla are all absent. Moreover, in agenesia of dorsal pancreas, the pancreatic bed is frequently filled by the stomach or small bowel (dependent-stomach or dependent-intestine signs) [7].