Teaching Case

A 50-year-old lady presented with chronic upper abdominal pain with episodes of exacerbation and remission with the use of oral analgesics. She also complained of weight loss and steatorrhoea for the past 6 months. On examination she was found to have elevated blood sugar 280 mg/dl.

CT study of abdomen revealed multiple intraductal calculi in the region of pancreatic head. These were associated with near total lipomatosis of the pancreatic parenchyma. No significant normal pancreatic glandular tissue was seen throughout the pancreatic bed. In light of the clinical details and based on the imaging findings, the diagnosis of pancreaticoliths with obstructive pancreatic lipomatosis was made.

Pancreatic lipomatosis refers to replacement of a part or of nearly all glandular components of the pancreas by lipomatous tissue. It has also been termed as fatty replacement, fatty infiltration, and adipose atrophy of the exocrine pancreas [1]. Pancreatic lipomatosis can be partial or complete.

Partial or incomplete lipomatosis is relatively common and is frequently encountered in diabetic, obese, and elderly patients [1, 3]. At cross-sectional imaging, 4 different types of uneven pancreatic lipomatosis have been described [6]: Type-1a (35% of cases) characterised by fatty replacement of the head with sparing of the uncinate process and peribiliary region; type-1b (36%), replacement of the head, neck, and body, with sparing of the uncinate process and peribiliary region; type-2a (12%), replacement of the head & the uncinate process, and sparing of the peribiliary region; and type-2b (18%), by near-total replacement of the pancreas with sparing of the peribiliary region.

Complete lipomatosis of pancreas is uncommon. It can be associated with congenital syndromes such as cystic fibrosis, Shwachman-Diamond or Johanson-Blizzard syndrome [6]. It has also been reported in patients with obstruction of the pancreatic duct by a tumour or a calculus [1-3, 5]. The exact pathogenesis of pancreatic lipomatosis is still not well established. The majority of the patients remain asymptomatic, however, complete lipomatosis can lead to exocrine insufficiency with resultant malabsorption and steatorrhoea [3]. These patients generally have a poorer outcome and frequently need pancreatic enzyme supplementation in combination with strict dietary modifications. On ultrasound, pancreatic lipomatosis manifests as hyperreflective pancreas, at times making differentiation difficult from the adjacent retroperitoneal fat. Cross-sectional imaging is particularly useful in confirming pancreatic lipomatosis and also detecting specific aetiologies such as obstructive calculi or neoplasms. The duct in case of obstructive calculi and neoplasm is characteristically stenotic rather than dilated, and typically has a smooth wall [3]. Complete lipomatosis needs to be distinguished from agenesis of dorsal pancreas. Dorsal pancreatic agenesis is characterised by the absence of body and tail of pancreas and frequently the distal pancreatic is filled by stomach or intestine (dependent-stomach or dependent-intestine signs), which abut splenic vein. In contrast, in case of lipomatosis abundant fat tissue is observed anterior to the splenic vein [4].

It is thus imperative for the radiologist to be attentive to this condition and carefully look for any obstructive pancreatic ductal pathology in patient with lipomatosis. The condition, if not timely detected and treated, can result in pancreatic exocrine insufficiency and malabsorption [3].