Pancreatic Lipomatous Pseudohypertrophy

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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 Pancreas appears identical to lipomatous pseudohypertrophy, but with very different clinical presentation

image Clinical presentation is very different, starting in childhood
• Pancreatic senescent changes

image Pancreatic atrophy, but rarely clinically significant
image Usually more uneven fatty replacement of pancreas
image Also associated with obesity, diabetes, and steroid use
• Pancreatic focal fatty infiltration

image Usually limited to head-uncinate or body-tail segments
• Shwachman-Diamond syndrome

image Rare congenital disorder characterized by pancreatic insufficiency, bone marrow dysfunction, and short stature
• Retroperitoneal liposarcoma

image Often confused with lipomatous pseudohypertrophy due to massive fatty hypertrophy in retroperitoneum

PATHOLOGY

• Exact etiology is unknown
• Possibly congenital, but may require inciting factor such as cirrhosis, viral infection, or abnormal metabolism

CLINICAL ISSUES

• Usually incidental finding on CT or in autopsy
• Rarely, patients require enzyme therapy due to exocrine deficiency
image
(Left) Axial NECT in a woman with alcoholic cirrhosis shows typical cirrhotic morphology of the liver (nodular with widened fissures) and ascites.

image
(Right) Axial NECT in the same patient shows diffuse enlargement and fatty replacement of the pancreas image, which mimics findings seen in cystic fibrosis.
image
(Left) Axial T1WI C+ FS MR in the same patient shows the lipomatous pseudohypertrophy with diffuse dropout of signal throughout the body of the pancreas image due to fat suppression.

image
(Right) Axial opposed-phase T1WI in the same patient shows high signal throughout the pseudohypertrophied pancreas image.

TERMINOLOGY

Definitions

• Enlargement of pancreas due to replacement by adipose tissue with atrophy of normal exocrine parenchyma

IMAGING

General Features

• Best diagnostic clue

image Diffuse enlargement and fatty replacement of pancreas
image No imaging or clinical signs of cystic fibrosis
• Location

image Focal (tail, body, head) or diffuse involvement (more common)
• Size

image Usually 2-4x size of normal pancreas
• Morphology

image Homogeneous fatty replacement

Imaging Recommendations

• Best imaging tool

image CT or MR

CT Findings

• Homogeneous, focal or diffuse enlargement of pancreas with fatty replacement of affected pancreatic parenchyma

image No imaging or clinical signs of cystic fibrosis
• Usually no evidence of ductal obstruction (pancreatic or biliary) or discrete mass
• Mass effect upon adjacent structures due to pancreatic enlargement is common

MR Findings

• Appearance of pancreas follows fat signal on all sequences

DIFFERENTIAL DIAGNOSIS

Cystic Fibrosis

• Appearance of pancreas identical to lipomatous pseudohypertrophy
• Patients with cystic fibrosis can develop cirrhosis
• Unique clinical presentation, beginning in childhood

image Chronic infections in lungs, failure to thrive, bowel obstruction, etc.

Pancreatic Senescent Changes

• Age-related lipomatosis, fibrosis, and ductal epithelial alterations
• Pancreatic atrophy, but rarely clinically evident or significant

image Usually more uneven, heterogeneous fatty replacement of pancreas
• Also associated with obesity, diabetes, and steroid use

Pancreatic Focal Fatty Infiltration

• Normal-sized pancreas
• Partial fatty replacement of acinar parenchyma
• Often limited to either head-uncinate or body-tail segments

image Corresponds to fetal ventral and dorsal segments

Shwachman-Diamond Syndrome

• Rare congenital disorder characterized by pancreatic insufficiency, bone marrow dysfunction, and short stature

Retroperitoneal Liposarcoma

• Lipomatous pseudohypertrophy often confused with liposarcoma due to massive fatty hypertrophy in retroperitoneum and mass effect on adjacent structures

PATHOLOGY

General Features

• Etiology

image Unknown
image Possibly congenital, but may require inciting factor, such as cirrhosis, viral infection, or abnormal metabolism
• Associated abnormalities

image Chronic advanced liver disease, parkinsonism, COPD

Gross Pathologic & Surgical Features

• Enlargement of pancreas with focal/diffuse fatty replacement of normal pancreatic tissue
• No evidence of capsule

Microscopic Features

• Marked atrophy and loss of exocrine glandular elements
• Replacement by mature adipose tissue
• Preservation of ducts and islets of Langerhans
• No evidence of fat necrosis or underlying pancreatitis

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Asymptomatic
image Can rarely result in pancreatic exocrine dysfunction
• Other signs/symptoms

image Mass effect (common), bile duct obstruction (rare)

Demographics

• Epidemiology

image Rare, with only a few sporadic reports in literature
image No gender predominance
image Usually young patients, but increasingly reported in older patients

Natural History & Prognosis

• Very benign course
• Usually incidental finding on CT or in autopsy
• Rarely, patients require enzyme therapy due to exocrine deficiency

DIAGNOSTIC CHECKLIST

Image Interpretation Pearls

• Look for clinical or imaging evidence of cystic fibrosis as alternative diagnosis
image
Axial NECT of a patient with cirrhosis and ascites shows enlargement and fatty replacement of the pancreas image that mimics findings seen in cystic fibrosis.

image
In a patient with lipomatous pseudohypertrophy of the pancreas, note the enlargement and fatty replacement of the pancreas image, which mimics findings seen in cystic fibrosis. The clinical presentation for patients with cystic fibrosis is very different, with chronic pulmonary infections and other problems starting in early childhood.
image
Axial CECT in a 40-year-old man with longstanding Crohn disease shows marked fatty infiltration of the pancreas image but no enlargement of the gland. The patient had no symptoms of pancreatic disease, and the fatty infiltration of the pancreas is believed to be due to chronic steroid use.

SELECTED REFERENCES

1. Izumi, S, et al. A minute pancreatic ductal adenocarcinoma with lipomatous pseudohypertrophy of the pancreas. JOP. 2011; 12(5):464–468.

Altinel, D, et al. Lipomatous pseudohypertrophy of the pancreas: a clinicopathologically distinct entity. Pancreas. 2010; 39(3):392–397.

Yasuda, M, et al. A case of lipomatous pseudohypertrophy of the pancreas diagnosed by typical imaging. JOP. 2010; 11(4):385–388.

Flohr, T, et al. Liver transplantation in a patient with primary sclerosing cholangitis suffering from lipomatous pseudohypertrophy of the pancreas. Transpl Int. 2008; 21(1):89–91.

Kuroda, N, et al. Lipomatous pseudohypertrophy of the pancreas: further evidence of advanced hepatic lesion as the pathogenesis. Pathol Int. 2003; 53(2):98–101.