DOI:10.2214/AJR.05.0555
AJR 2006; 187:W607-W609
© American Roentgen Ray Society
Heterotopic Pancreas: Presentation as Jejunal Tumor
Kumaresan Sandrasegaran1,
Dean D. Maglinte1 and
Oscar W. Cummings1
1 All authors: Indiana University School of Medicine, Department of Radiology,
UH 0279, 550 N University Boulevard, Indianapolis, IN 46202.
Received March 29, 2005;
accepted after revision May 25, 2005.
Address correspondence to K. Sandrasegaran.
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Keywords: abdominal imaging • CT • pancreatitis • small bowel disease
Introduction
With the advent of MDCT, increasing attention is being paid to small bowel
disease. We present a case in which the original CT report of a small bowel
tumor was at variance with the clinical picture of acute abdominal
inflammation. Surgical pathology showed inflammation of a heterotopic pancreas
in the proximal jejunum. Heterotopic pancreas is the presence of pancreatic
tissue outside the normal location and lacking ductal or vascular continuity
with the main gland. There are case series of the CT appearance of heterotopic
pancreas in the stomach
[1-4].
We are not aware of reports on the CT appearance of heterotopic pancreas in
the jejunum. We discuss the relevant imaging and clinical findings.
A 65-year-old man presented with a 2-day history of diffuse abdominal pain
and vomiting. There was epigastric tenderness on examination and initial
laboratory tests revealed raised amylase and leukocytosis. The working
clinical diagnosis was acute pancreatitis. CT examination with oral (500 mL of
2% diatrizoate meglumine over 1 hour; Gastrografin, Bracco) and IV (150 mL of
iopamidol; Isovue-300, Bracco) contrast using a 4-MDCT scanner (Mx8000,
Philips Medical Systems) was performed. An effective slice thickness of 6.5 mm
and a longitudinal reconstruction interval of 3.0 mm were used. An exophytic
brightly and homogeneously enhancing 5-cm jejunal mass was seen (Figs.
1A and
1B). There was surrounding
mesenteric edema and segmental asymmetric thickening of jejunal wall. Mild
distention of the stomach and duodenum was noted. The orthotopic pancreas
appeared normal (Fig. 1C) and
there was no evidence of adenopathy. A diagnosis of jejunal tumor, probably
gastrointestinal stromal tumor or lymphoma, was made on the prospective CT
report. In retrospect, there was a thin, tubular, low-density structure within
the mass that is best appreciated on coronal reformation
(Fig. 1D). At laparotomy 2 days
later, a mass measuring 6 x 8 cm and the first 15 cm of jejunum were
removed, followed by primary anastomosis. Frozen sections and subsequent
surgical pathology revealed heterotopic pancreas
(Fig. 1E) with
pancreatitis.
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Fig. 1A —65-year-old man with diffuse abdominal pain and vomiting.
Axial CT images show enhancing mass closely applied to proximal jejunum
(black arrowheads). Jejunal wall is asymmetrically thickened
(arrow). Normal pancreatic head (white arrowhead) is seen in
B.
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Fig. 1B —65-year-old man with diffuse abdominal pain and vomiting.
Axial CT images show enhancing mass closely applied to proximal jejunum
(black arrowheads). Jejunal wall is asymmetrically thickened
(arrow). Normal pancreatic head (white arrowhead) is seen in
B.
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Fig. 1D —65-year-old man with diffuse abdominal pain and vomiting.
Coronal reformat shows vertical extent of mass (arrowhead). There is
thin, low-density, linear structure in mass, possibly pancreatic duct. Note
surrounding mesenteric edema (arrow).
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Fig. 1E —65-year-old man with diffuse abdominal pain and vomiting. H
and E stain (x200). Section of jejunal wall showing normal mucosa
(black arrowhead) with pancreatic acini (white arrowheads)
in submucosa. Small pancreatic-type interlobular duct with squamous metaplasia
(arrow) is also present. Bulk of heterotopic pancreas was present in
small bowel mesentery.
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Discussion
The pancreas is derived from several endodermal invaginations of the
primitive duodenal wall. The dorsal diverticulum becomes the body and tail,
and the ventral portion becomes the head of the pancreas. The most accepted
theory regarding the origin of heterotopic pancreas is that one or more of
these invaginations remain within the bowel wall and become incorporated in
the upper gastrointestinal tract. Pancreatic heterotopia is seen incidentally
in approximately 2-5% of autopsies
[5]; thus, this entity is
usually asymptomatic. The most frequent sites of heterotopia are the stomach
and the duodenum. The jejunum is a less common site. Case reports show
heterotopic pancreas in the esophagus, mediastinum, gallbladder, omentum,
spleen, fallopian tubes, and lymph nodes
[6,
7].
Despite its congenital origin, heterotopic pancreas clinically manifests in
older adults, often in the sixth decade of life. Common presentations include
gastric outlet obstruction and upper gastrointestinal bleeding. Small bowel
obstruction from heterotopic pancreas is rare. Adenocarcinoma, islet cell
tumors, and cystic tumors are reported to occur in the heterotopic pancreas
[1,
6].
On upper gastrointestinal contrast series, heterotopic pancreas is
typically seen as a submucosal antral mass, sometimes with a central
umbilication. Recently, 16 cases of the CT appearance of gastric heterotopia
were reported
[1-3].
Most heterotopias enhance brightly, similar to the orthotopic pancreas. The
lesions are more obvious if water is used as oral contrast. Reduced
enhancement may be seen with inflammation of heterotopic pancreas.
In our case, the CT findings of an exophytic enhancing mass arising from
the jejunum with proximal obstruction was mistaken for a submucosal neoplasm.
In retrospect, there were features that would have supported inflammation of a
heterotopic pancreas. The clinical findings favored pancreatitis, but the
pancreas appeared normal on CT. There was considerable mesenteric inflammation
adjacent to the jejunal mass and coronal reformats showed the presence of a
possible duct within this mass.
In conclusion, it is important to remember heterotopic pancreas when
confronted with an enhancing exophytic jejunal mass on CT, particularly if the
clinical presentation is one of acute abdomen.
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Introduction
Discussion
