Ectopic Pancreatic Tissue

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 19/07/2015

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 Well-defined, smoothly marginated, round/oval submucosal mass with central umbilication

image Reflux of contrast into rudimentary duct-like structure may extend below central pit
• CT findings

image Often too small to be detected
image Round or oval mass with protrusion into gut lumen
image May have well-defined or ill-defined margins on CT
image Enhancement pattern is variable

– Acini-dominant ectopic pancreas shows homogeneous, avid enhancement
– Others types more heterogeneous (or even cystic)
– Overlying mucosa of bowel often avidly enhancing
• MR findings: Ectopic pancreas is isointense on all pulse sequences with main pancreas (including DWI/ADC)

TOP DIFFERENTIAL DIAGNOSES

• Gastric GIST
• Other gastric hypervascular submucosal lesions (glomus tumor, carcinoid, GIST)
• Gastric ulcer
• Gastric carcinoma
• Gastric metastases and lymphoma

CLINICAL ISSUES

• Most patients are asymptomatic and ectopic pancreas is usually an incidental finding
• Can be complicated by bleeding or mucosal ulceration and patients present with epigastric pain and melena
• Can undergo any of the inflammatory or neoplastic abnormalities of main pancreas including acute/chronic pancreatitis and development of malignancy
image
(Left) Axial CECT demonstrates a mural mass image in the body of the stomach. Note that the mass enhances similarly to the normal pancreas. Endoscopic biopsy revealed ectopic pancreatic tissue.

image
(Right) Axial CECT in a patient with abdominal pain demonstrates a cystic intramural mass image within the distal stomach, found to represent ectopic pancreas after surgery. Ectopic pancreas can appear homogeneous, heterogeneous, or cystic depending on its internal mixture of acini, ducts, and islet cells.
image
(Left) Upper GI series spot film shows a small antral mass with intact mucosa. A central “dot” of barium image can be seen filling a rudimentary duct.

image
(Right) Upper GI image shows a small, smooth, intramural mass image along the greater curvature of the antrum without central umbilication. Only 45% of patients with ectopic pancreas will have central umbilication on a barium study. In the absence of this sign, it is difficult to distinguish ectopic pancreas from other intramural masses, such as metastasis or GIST.

TERMINOLOGY

Abbreviations

• Ectopic pancreatic tissue (EPT)

Synonyms

• Pancreatic rests; heterotopic, aberrant, accessory pancreas

Definitions

• Pancreatic tissue located outside of normal confines of pancreas and lacking any anatomic or vascular connection with main pancreas

IMAGING

General Features

• Best diagnostic clue

image Small submucosal gastric mass with central umbilication 

– Central umbilication (45% of cases): Orifice of rudimentary duct through which ectopic pancreatic tissue (EPT) drains into gastric lumen
• Location

image 90% of all cases found in upper GI tract (stomach, duodenum, or proximal jejunum)

– Most commonly gastric antrum (< 6 cm from pylorus)
– Can rarely arise in ileum, Meckel diverticulum, liver, biliary tract, spleen, omentum, mesentery, lung, mediastinum, fallopian tube, esophagus, colon
image Primarily arise in submucosa (73%); can also be located in muscular layer (17%) or subserosa (10%)

– 2nd most common gastric submucosal mass (behind only mesenchymal lesions such as GI stromal tumors)
• Size

image Nodule: 0.5-2 cm; may be up to 5 cm in diameter
image Pit: May be 5 mm in diameter and 10 mm in length
• Morphology

image Submucosal layer: Appears as well-defined flat or nodular projection into gut lumen with intact overlying mucosa
image Muscularis or subserosal layers: Produces smooth bulge or area of wall thickening
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