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(Radiology. 2000;217:139-144.)
© RSNA, 2000

Gastrointestinal Imaging

Heterotopic Pancreas in the Stomach: CT Findings1

June-Sik Cho, MD, Kyung-Sook Shin, MD, Soon-Tae Kwon, MD, Jin-Whan Kim, MD, Chang-June Song, MD, Seung-Moo Noh, MD, Dae-Young Kang, MD, Hyung-Yul Kim, MD and Hyung-Keun Kang, MD

1 From the Departments of Radiology (J.S.C., K.S.S., S.T.K., J.W.K., C.J.S.), Surgery (S.M.N.), and Pathology (D.Y.K.), Chungnam University Hospital Daesa-dong 640, Joong-Ku, Taejon 301-040, Korea; the Department of Radiology, Sun General Hospital, Taejon, Korea (H.Y.K.); and the Department of Radiology, Chunnam University Hospital, Kwangju, Korea (H.K.K.). Received August 27, 1999; revision requested October 7; revision received January 19, 2000; accepted February 7. Address correspondence to J.S.C. (e-mail: jscho@cnuh.chungnam.ac.kr).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To describe the computed tomographic (CT) findings of heterotopic pancreas in the stomach.

MATERIALS AND METHODS: CT findings in 12 patients with heterotopic pancreas in the stomach were reviewed. Surgical resection (n = 11) or endoscopic excision (n = 1) was performed in cases of symptomatic heterotopic pancreas (n = 4), suspected submucosal tumors (n = 7), and gastric carcinoma (n = 1). Seven patients underwent helical CT with water as an oral contrast agent; five underwent nonhelical CT with water-soluble contrast material.

RESULTS: Nine heterotopic pancreata were in the antrum and one each was in the body, fundus, and perigastric fat. Seven lesions were on the greater curvature aspect; five, on the lesser curvature aspect. Common CT findings were well-defined oval or round masses with smooth or serrated margins in the gastric antral wall. Four of the seven lesions in which helical CT was performed enhanced similarly to normal pancreas. Preoperatively, CT depicted 11 of the 12 lesions, but CT findings were interpreted correctly as heterotopic pancreas in only two; the remaining 10 were misinterpreted as other lesions. Atypical findings were cystic dilatation of heterotopic pancreatic duct in two, unusual location in the fundus or perigastric fat in two, and malignant transformation in one.

CONCLUSION: CT findings of heterotopic pancreas in the stomach appear to be nonspecific for diagnosis, except for location.

Index terms: Pancreas, heterotopic (new), 72.314 • Stomach, abnormalities, 72.314 • Stomach, CT, 72.1211 • Stomach, neoplasms, 72.312


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Heterotopic pancreas in the stomach is an uncommon abnormality, and its incidence in autopsy series ranges from 0.6% to 14.0% (1–3). Although its incidence in this autopsy series (2,3) was relatively high, heterotopic pancreas in the stomach is discovered much less frequently during life. These lesions usually are small, often are asymptomatic, and are discovered incidentally during surgery or autopsy (3,4). However, some patients have epigastric pain, upper gastrointestinal bleeding, and occasional gastric outlet obstruction (2–8). In a few cases, the complications of heterotopic pancreas, which include pancreatitis, pseudocyst, cyst formation, insulinoma, adenoma, and malignant transformation, have been reported (2–4,9,10).

The characteristic radiographic appearance of heterotopic pancreas in the stomach at upper gastrointestinal examination has been described as that of a small broad-based submucosal mass in the antrum, with a central umbilication that represents a rudimentary pancreatic duct; the mass resembles leiomyoma or other submucosal tumors such as carcinoid or intramural metastasis (4–8). The mass usually is located along the greater curvature of the stomach, often in the prepyloric area within 6 cm of the pyloric canal (3–8). On occasion, heterotopic pancreas appears as a mass with an irregular surface indistinguishable from an adenomatous polyp or a polypoid carcinoma (4,8). Therefore, the radiographic findings of heterotopic pancreas in the stomach may easily be misinterpreted as a gastric tumor. Although the characteristic radiographic findings of heterotopic pancreas in the stomach have been described in the literature (4–7), to our knowledge no investigators have described the computed tomographic (CT) findings of heterotopic pancreas in the English-language radiology literature. The purpose of this retrospective review of cases was to describe the CT findings of heterotopic pancreas in the stomach, with histopathologic correlation.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Patients
In the patients who underwent abdominal CT at Chungnam University Hospital and Chunnam University Hospital from March 1992 to October 1998, 12 with histopathologically proved heterotopic pancreas in the stomach at surgical resection (n = 11) and at endoscopic excision (n = 1) were included in this study. The age range of the patients was 18–73 years (mean age, 41 years). Seven patients were men and five were women. Prior to CT, all 12 patients underwent double-contrast upper gastrointestinal examination, and 10 underwent endoscopy.

Nine patients had epigastric pain, and one had melena. The remaining two patients had no symptoms. Ten patients with symptomatic lesions underwent CT for further evaluation of the extent of the lesion before confirmation of the endoscopic biopsy results. Four of these 10 patients with apparent symptomatic lesions received a diagnosis of heterotopic pancreas by means of endoscopic biopsy. The remaining six patients did not receive a diagnosis by means of endoscopic biopsy and were classified as having an indeterminate submucosal tumor. Nine of 10 patients’ symptomatic lesions were treated with surgical wedge resection, and one was treated with endoscopic excision. After the removal of the heterotopic pancreas, follow-up was performed in six patients, and symptoms were improved in all six. Of two patients with asymptomatic lesions, one patient had a lesion that was detected incidentally as a submucosal mass at endoscopic screening for the early detection of gastric carcinoma, and the patient underwent CT for further evaluation. The lesion was removed with wedge resection under an indeterminate submucosal tumor because endoscopic biopsy did not result in a diagnosis. The other patient’s lesion was detected incidentally at CT for gastric cancer staging as a nodular lesion in the perigastric fat of the gastric antrum.

CT Techniques
Seven of the 12 patients underwent dual-phase helical CT with a HiSpeed Advantage scanner (GE Medical Systems, Milwaukee, Wis). The remaining five patients underwent nonhelical CT with a model CT/T 9800 scanner (GE Medical Systems) or an Xpeed scanner (Toshiba Medical Systems, Tokyo, Japan) because a helical CT scanner was not available. To better depict gastric lesions, 600–1,000 mL of water was administered as an oral contrast agent before dual-phase helical CT. A total of 150 mL of nonionic contrast material, 300 mg/mL of iodine (iopromide [Ultravist; Schering, Berlin, Germany]), was administered with a power injector (MCT Plus; Medrad, Pittsburgh, Pa) at a rate of 3–5 mL/sec for 30–50 seconds. We used an 18-20-gauge intravenous catheter (Jelco; Ethicon SPA, Rome, Italy) for the intravenous injection of contrast material into the antecubital vein. In accordance with the CT protocol for gastric tumors at Chungnam University Hospital, we obtained dual-phase images during the portal and equilibrium phases. Dual-phase helical CT scans were obtained 60 seconds (portal phase) and 3 minutes (equilibrium phase) after the start of the intravenous administration of a bolus of contrast material. Helical CT was performed with a 1-second scanning time, a 1:1 pitch, 5- or 7-mm section thickness, and 5- or 7-mm reconstruction interval. The images were obtained from the right side of the diaphragmatic dome to the inferior margin of the liver. The portal phase images were obtained for improved lesion conspicuity and for improved depiction of small hepatic metastases and lymphadenopathy. The equilibrium phase images were obtained to evaluate tumor extent with delayed enhancement of the tumors.

Nonhelical CT was performed with a continuous 5- or 10-mm section thickness and 5- or 10-mm intervals. Before nonhelical CT, 600–800 mL of water-soluble oral contrast material (2% meglumine amidotrizoate solution [Gastrografin; Schering, Berlin, Germany) was administered. A total of 100–120 mL of nonionic contrast material (300 mg of iodine per milliliter) was administered intravenously.

Image Analysis
The CT findings in 12 patients with heterotopic pancreas in the stomach were interpreted prospectively by two abdominal radiologists (J.S.C. and K.S.S.) without prior knowledge of the upper gastrointestinal study or endoscopic biopsy findings. When there was disagreement in CT readings, the final decision was made with a consensus of the two investigators. The size, location, and contrast material enhancement patterns of the lesions on the CT scans were analyzed. The lesions were measured by using an electronic caliper at the workstation or operator console. The degree of contrast material enhancement of the lesions on the helical CT scans was qualitatively analyzed relative to normal pancreatic enhancement. The CT images were compared retrospectively with the surgical and histopathologic findings to better characterize the CT findings of heterotopic pancreas.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
DISCUSSION
 REFERENCES
 
Of the 12 cases of heterotopic pancreas, nine (75%) were in the gastric antrum, one (8%) was in the body, one (8%) was in the fundus, and one (8%) was in the perigastric fat of the antrum on the greater curvature aspect. Heterotopic pancreas was on the greater curvature aspect in seven (58%) patients and on the lesser curvature aspect in five (42%) patients.

The findings at upper gastrointestinal examination in 12 patients were interpreted as heterotopic pancreas in three, submucosal tumor in seven, and gastric carcinoma in two. Endoscopic findings in 10 patients were interpreted as heterotopic pancreas in two, submucosal tumor in six, and gastric carcinoma in two. In 12 patients, central umbilications suggesting a rudimentary duct of the heterotopic pancreas were identified in only three (25%) patients. In the remaining nine patients, neither radiography nor endoscopy demonstrated the presence of central umbilication in the lesions, and they were misinterpreted as submucosal tumors or as gastric carcinomas.

Preoperatively, CT depicted 11 (92%) of the 12 lesions on helical CT scans or on nonhelical CT scans. However, without prior information on the upper gastrointestinal study or endoscopic biopsy, CT findings were prospectively interpreted correctly as heterotopic pancreas, which was located along the greater curvature of the prepyloric antrum, in only two (17%) cases. The remaining 10 (83%) cases were misinterpreted as leiomyoma in four, carcinoid tumor in three, submucosal scirrhous carcinoma in two, and lymphadenopathy in one. Each patient had a single lesion. The long-axis diameter and the height of the lesions on CT scans was 1.0 x 0.8–5.0 x 3.7 cm (mean size, 2.7 x 1.9 cm). Nine (75%) of the 12 lesions were less than 3.0 cm. The remaining three (25%) were 3.0–5.0 cm. The shapes of the lesions on CT scans were oval in eight cases, round in three, and lobulated in one.

In six of the seven patients who underwent dual-phase helical CT with water as an oral contrast agent, the portal phase images depicted the submucosal location of the lesions with well-enhanced, intact, overlying mucosa (Figs 1–3). Of these six patients, four had lesions with homogeneous or heterogeneous enhancement similar to that of normal pancreas (Fig 3). The appearances of these six patients’ lesions on helical CT scans were as follows: an oval well-defined submucosal mass with smooth or serrated margins (Figs 1, 3) in four patients; an oval submucosal mass with indistinct margins (Fig 2) in one; and a large infiltrating submucosal mass in one. In one patient with a large infiltrating lesion, double-contrast upper gastrointestinal examination showed a sharply demarcated broad-based submucosal mass in the gastric antrum and body with a double-contoured, small, round area within it (Fig 4a). Helical CT scans obtained during the portal phase showed a broad-based, submucosal infiltrating mass with marked enhancement and with a small submucosal cyst at the top (Fig 4b). Microscopic examination confirmed the infiltration of the heterotopic pancreatic tissue in the submucosa into the muscle layer, which corresponded well with helical CT findings (Fig 4c). A small cystic area was a markedly dilated anomalous duct of heterotopic pancreas, which was bordered by pancreatic excretory epithelium. This small cystic area within the lesion was seen in two cases. No communication between the cystic dilatation of heterotopic pancreatic duct and the gastric lumen was found.



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  		Figure 1. Heterotopic pancreas in the gastric antrum in a 37-year-old man. Transverse helical water-enhanced CT scan shows a small round submucosal lesion (arrows) with well-defined margins in the wall of the prepyloric antrum on the anterior wall along the greater curvature. Note an enhancing overlying mucosal layer (arrowheads). The lesion was confirmed as heterotopic pancreas at endoscopic excision.

 


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  		Figure 2. Heterotopic pancreas in the gastric antrum in an 18-year-old man with epigastric pain. Transverse helical water-enhanced CT scan shows a small oval submucosal lesion (arrows) with moderate enhancement and with indistinct margins in the wall of prepyloric antrum on the posterior wall near the greater curvature. Note an enhancing overlying mucosal layer (arrowheads).

 


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  		Figure 3. Heterotopic pancreas in the gastric antrum in a 39-year-old man. Transverse helical water-enhanced CT scan shows a well-defined oval submucosal mass (black arrows) with smooth margins in the posterior wall of the gastric antrum that mimics hypervascular submucosal tumor and has contrast material enhancement similar to that of normal pancreas (arrowheads). Note the markedly enhancing mild thickening of the overlying mucosal layer (white arrows), which was confirmed as chronic inflammation at microscopic examination.

 


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  		Figure 4a. Heterotopic pancreas in the gastric antrum and body in a 36-year-old woman. (a) Spot radiograph from double-contrast upper gastrointestinal study shows a large lobulated submucosal mass (arrows) on the posterior wall near the lesser curvature of the gastric antrum and body, with a smooth mucosal surface and double-contoured round areas (arrowheads) within. (b) Transverse helical water-enhanced CT scan shows a broad-based submucosal mass (arrowheads) with a small cystic area (arrow) and strongly enhancing infiltration into the muscle layer. The small cystic area was found to be cystic dilatation of anomalous pancreatic duct. The infiltrating lesion into the muscle layer was proved to be heterotopic pancreatic tissue at microscopic examination. (c) Photomicrograph of histopathologic specimen shows pancreatic tissue composed of pancreatic acini, pancreatic ducts (arrowheads), and islets of Langerhans (short arrows). Note the infiltrating pancreatic tissue (long arrows) into the muscle layer. (Hematoxylin-eosin stain; original magnification, x40.)

 


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  		Figure 4b. Heterotopic pancreas in the gastric antrum and body in a 36-year-old woman. (a) Spot radiograph from double-contrast upper gastrointestinal study shows a large lobulated submucosal mass (arrows) on the posterior wall near the lesser curvature of the gastric antrum and body, with a smooth mucosal surface and double-contoured round areas (arrowheads) within. (b) Transverse helical water-enhanced CT scan shows a broad-based submucosal mass (arrowheads) with a small cystic area (arrow) and strongly enhancing infiltration into the muscle layer. The small cystic area was found to be cystic dilatation of anomalous pancreatic duct. The infiltrating lesion into the muscle layer was proved to be heterotopic pancreatic tissue at microscopic examination. (c) Photomicrograph of histopathologic specimen shows pancreatic tissue composed of pancreatic acini, pancreatic ducts (arrowheads), and islets of Langerhans (short arrows). Note the infiltrating pancreatic tissue (long arrows) into the muscle layer. (Hematoxylin-eosin stain; original magnification, x40.)

 


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  		Figure 4c. Heterotopic pancreas in the gastric antrum and body in a 36-year-old woman. (a) Spot radiograph from double-contrast upper gastrointestinal study shows a large lobulated submucosal mass (arrows) on the posterior wall near the lesser curvature of the gastric antrum and body, with a smooth mucosal surface and double-contoured round areas (arrowheads) within. (b) Transverse helical water-enhanced CT scan shows a broad-based submucosal mass (arrowheads) with a small cystic area (arrow) and strongly enhancing infiltration into the muscle layer. The small cystic area was found to be cystic dilatation of anomalous pancreatic duct. The infiltrating lesion into the muscle layer was proved to be heterotopic pancreatic tissue at microscopic examination. (c) Photomicrograph of histopathologic specimen shows pancreatic tissue composed of pancreatic acini, pancreatic ducts (arrowheads), and islets of Langerhans (short arrows). Note the infiltrating pancreatic tissue (long arrows) into the muscle layer. (Hematoxylin-eosin stain; original magnification, x40.)

 
In the remaining patient, who underwent helical CT for the preoperative staging of gastric carcinoma (Fig 5a), a nodule was detected in the perigastric fat of the prepyloric antrum on the greater curvature aspect (Fig 5b). The lesion was enhancing poorly at portal phase CT and was misinterpreted as an enlarged lymph node (Fig 5b). This lesion, at examination of the gross specimen, was a yellowish oval mass with serrated margins that was adherent to the serosal surface of the prepyloric antrum (Fig 5c). Microscopic examination revealed a heterotopic pancreas with malignant transformation to mucinous cystadenocarcinoma. No enlarged lymph node was found. Surgical and histopathologic findings indicated no connection between the heterotopic pancreas and the adjacent normal pancreas.



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  		Figure 5a. Heterotopic pancreas in the perigastric fat of the gastric antrum in a 73-year-old woman with early gastric carcinoma in the gastric antrum. (a) Transverse helical water-enhanced CT scan shows a focal wall thickening (arrows) of the gastric antrum with mild enhancement, which was confirmed as an early gastric carcinoma. (b) Transverse helical CT scan obtained at a level slightly caudal to a shows a round mass (arrows) that mimics lymph node enlargement in the perigastric fat between the gastric antrum and the pancreas. Note the poorly enhancing nodular mass, as compared with the markedly enhancing adjacent normal pancreas (arrowheads). (c) Gross specimen shows an oval mass with a fine nodular surface (large arrow) that is adherent to the serosal surface of the prepyloric antrum; this was confirmed histopathologically as heterotopic pancreas with malignant transformation to mucinous cystadenocarcinoma. Note the small depressed area with irregular converging folds (small arrows) due to early gastric carcinoma of the prepyloric antrum.

 


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  		Figure 5b. Heterotopic pancreas in the perigastric fat of the gastric antrum in a 73-year-old woman with early gastric carcinoma in the gastric antrum. (a) Transverse helical water-enhanced CT scan shows a focal wall thickening (arrows) of the gastric antrum with mild enhancement, which was confirmed as an early gastric carcinoma. (b) Transverse helical CT scan obtained at a level slightly caudal to a shows a round mass (arrows) that mimics lymph node enlargement in the perigastric fat between the gastric antrum and the pancreas. Note the poorly enhancing nodular mass, as compared with the markedly enhancing adjacent normal pancreas (arrowheads). (c) Gross specimen shows an oval mass with a fine nodular surface (large arrow) that is adherent to the serosal surface of the prepyloric antrum; this was confirmed histopathologically as heterotopic pancreas with malignant transformation to mucinous cystadenocarcinoma. Note the small depressed area with irregular converging folds (small arrows) due to early gastric carcinoma of the prepyloric antrum.

 


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  		Figure 5c. Heterotopic pancreas in the perigastric fat of the gastric antrum in a 73-year-old woman with early gastric carcinoma in the gastric antrum. (a) Transverse helical water-enhanced CT scan shows a focal wall thickening (arrows) of the gastric antrum with mild enhancement, which was confirmed as an early gastric carcinoma. (b) Transverse helical CT scan obtained at a level slightly caudal to a shows a round mass (arrows) that mimics lymph node enlargement in the perigastric fat between the gastric antrum and the pancreas. Note the poorly enhancing nodular mass, as compared with the markedly enhancing adjacent normal pancreas (arrowheads). (c) Gross specimen shows an oval mass with a fine nodular surface (large arrow) that is adherent to the serosal surface of the prepyloric antrum; this was confirmed histopathologically as heterotopic pancreas with malignant transformation to mucinous cystadenocarcinoma. Note the small depressed area with irregular converging folds (small arrows) due to early gastric carcinoma of the prepyloric antrum.

 
In five patients who underwent nonhelical CT with 2% meglumine amidotrizoate solution as an oral contrast agent, lesions were oval in three, round in one, and lobulated in one. It was difficult to identify the submucosal locations of the lesions on CT scans because of the use of a positive oral contrast agent. Lesions in four of these five patients appeared as focal wall thickening of the gastric antrum, with well-defined smooth margins at CT. Although the contrast-enhanced intact mucosal layer overlying the lesions was not seen, CT findings in these lesions were suggestive of leiomyoma. The remaining heterotopic pancreas appeared as a large submucosal mass in the gastric antrum on an upper gastrointestinal series (Fig 6a). However, the lesion appeared on nonhelical CT scans as a lobulated mass that mimicked polypoid carcinoma (Fig 6b).



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  		Figure 6a. Heterotopic pancreas in the gastric antrum in a 60-year-old man. (a) Spot radiograph from double-contrast upper gastrointestinal study shows a large lobulated submucosal mass (arrows) in the gastric antrum with a smooth mucosal surface. (b) Transverse nonhelical contrast-enhanced CT scan shows a polypoid mass (arrows) in the posterior wall of the gastric antrum that mimics polypoid carcinoma. The overlying mucosal layer of the lesion is not identified because of the use of positive oral contrast material.

 


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  		Figure 6b. Heterotopic pancreas in the gastric antrum in a 60-year-old man. (a) Spot radiograph from double-contrast upper gastrointestinal study shows a large lobulated submucosal mass (arrows) in the gastric antrum with a smooth mucosal surface. (b) Transverse nonhelical contrast-enhanced CT scan shows a polypoid mass (arrows) in the posterior wall of the gastric antrum that mimics polypoid carcinoma. The overlying mucosal layer of the lesion is not identified because of the use of positive oral contrast material.

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
REFERENCES
 
Heterotopic pancreas is defined as pancreatic tissue that lacks anatomic and vascular continuity with the main body of the pancreas (3). However, the heterotopic pancreatic tissue may have all of the elements of the normal pancreas, which include pancreatic acini, pancreatic ducts, and islets of Langerhans, at histologic examination (4,5,7). The gross appearance of heterotopic pancreas in the stomach usually is a firm, yellow, finely lobulated nodule, which usually is located in the submucosa but sometimes extends into the muscularis or serosa (2–4,7,8).

Most often, heterotopic pancreas is found in the stomach, duodenum, or upper part of the jejunum (3–8). On occasion, this anomaly has been reported in the ileum, gallbladder, bile duct, spleen, umbilicus, regional papilla of the accessory pancreatic duct, omentum, mesentery, mediastinum, and Meckel diverticulum (3,5–7). Heterotopic pancreas in the stomach usually is 1–3 cm in diameter and usually is located along the greater curvature of the stomach, often in the gastric antrum within 6 cm of the pyloric canal (3–7). In our series, nine (75%) of the 12 cases of heterotopic pancreas were identified in this typical location—in the gastric antrum on the greater or lesser curvature. The remaining three cases of heterotopic pancreas were in atypical locations—in the body, fundus, or perigastric fat of the prepyloric antrum. Nine (75%) cases of heterotopic pancreas in our series were less than 3 cm in diameter, and the remaining three (25%) were 3–5 cm. The sizes and locations of the cases of heterotopic pancreas in our series were similar to those in previous reports (5–7).

The radiographic findings of heterotopic pancreas in the stomach at upper gastrointestinal examination have been described as a small usually round or oval mass that is sharply marginated and broad based (4–8). Therefore, heterotopic pancreas in the stomach may easily be misinterpreted as a gastric submucosal tumor such as leiomyoma. In our study, most of the lesions were identified at CT as oval or round masses in the gastric wall that were similar to other gastric tumors. In addition, heterotopic pancreas was difficult to differentiate from other submucosal tumors on nonhelical CT scans with positive oral contrast material.

It has been reported that water as an oral contrast agent provides adequate distention and satisfactory contrast for the depiction of subtle abnormalities in the gastric wall (11,12). For the improved depiction of gastric lesions, therefore, we performed dual-phase helical CT with water as an oral contrast agent in seven patients. On the portal phase images, we could better detect the submucosal location of heterotopic pancreas between the intraluminal water of the stomach and a well-enhanced overlying intact mucosal layer. In addition, four of these lesions had contrast enhancement similar to that of normal pancreas. Nevertheless, preoperatively, CT findings were interpreted correctly as heterotopic pancreas in two (17%) cases, and the remaining 10 (83%) cases were misinterpreted as leiomyoma in four, as carcinoid tumor in three, as submucosal scirrhous carcinoma in two, and as lymphadenopathy in one. Thus, our study results showed that it was difficult to distinguish heterotopic pancreas in the stomach from other submucosal tumors on CT scans, even though images with better contrast in the gastric wall were obtained at helical CT.

Kawamoto et al (13) reported endoscopic ultrasonographic (US) findings of five cases of heterotopic pancreas in the stomach and duodenum. In their study, cases of heterotopic pancreas appeared as submucosal masses with unclear or serrated margins, and two lesions appeared to infiltrate into the muscle layer. It is unfortunate that, to our knowledge, even endoscopic US cannot be used to confirm this diagnosis. In our study, however, four of the seven cases in which helical CT was performed with water as an oral contrast agent appeared to be well-defined submucosal masses with smooth or serrated margins, which corresponded well with the gross findings of heterotopic pancreas.

On occasion, heterotopic pancreas in the stomach appears at upper gastrointestinal study as a mass with an irregular surface that is indistinguishable from adenomatous polyp or even from polypoid carcinoma (4,7,8). In our series, two cases of heterotopic pancreas were misinterpreted as submucosal scirrhous carcinoma at CT because of the atypical locations and the highly atypical appearances of lesions that were considerably larger and more lobulated than the majority of cases of heterotopic pancreas. At helical CT, one of these two lesions had a broad-based submucosal infiltration with marked enhancement; the lesion was misinterpreted as a gastric carcinoma with submucosal infiltration. Histopathologic examination of the lesion, however, showed heterotopic pancreatic tissue in the submucosa that was infiltrating into the muscle layer; this corresponded well with the CT findings.

On rare occasions, complications, including pancreatitis, pseudocyst, cyst formation, insulinoma, adenoma, and malignant transformation, have been reported (2–10) in cases of gastric heterotopic pancreas. Claudon et al (9) reported that cyst formation in heterotopic pancreas in the stomach was related to cystic dilatation of an anomalous duct bordered by pancreatic excretory epithelium. In our series, a small cystic area within heterotopic pancreas on CT scans that was confirmed as a markedly dilated anomalous duct was seen in two patients. Malignant transformation of heterotopic pancreas is extremely rare, and, to our knowledge, there are only sporadic case reports available in the literature (10). In our series, one patient who underwent helical CT for the preoperative staging of gastric carcinoma had heterotopic pancreas that was detected incidentally as a nodular lesion in the perigastric fat of the prepyloric antrum. The lesion was poorly enhanced at the portal phase and was misinterpreted as lymphadenopathy. At microscopic examination, however, the nodule was shown to be heterotopic pancreas with malignant change to mucinous cystadenocarcinoma, and the lesion of the gastric antrum was an early gastric carcinoma that was confirmed as a moderately differentiated tubular adenocarcinoma. We consider that the lesion was poorly enhanced on the portal phase images because of abundant mucin content.

Heterotopic pancreas in the stomach has been described as a small asymptomatic lesion and usually is of no clinical importance (3–8). Therefore, if an accurate radiologic diagnosis can be made or if the lesion is asymptomatic, expectant management may be justified (3,14,15). However, it is necessary to resect heterotopic pancreas in the stomach if it causes symptoms or if a neoplastic condition cannot be excluded at radiologic or endoscopic examination (5,7,14,15). In our series, in contrast with those in previous reports, nine of the 12 patients had epigastric pain, and one had melena. Only four of these 10 patients with apparent symptoms received a diagnosis of heterotopic pancreas at endoscopic biopsy. Six patients with symptomatic lesions and one patient with an asymptomatic lesion had a failed diagnosis at endoscopic biopsy; preoperatively, seven patients’ lesions were misinterpreted as a submucosal tumor. The remaining patient’s lesion also was misinterpreted as lymphadenopathy. Therefore, all 12 patients’ lesions were treated with surgical resection or endoscopic excision. After treatment of the lesions, symptoms were improved in six patients who underwent follow-up evaluation.

With regard to the limitations of our study, 12 cases were selected in which CT was performed with different scanning protocols—nonhelical CT and helical CT—because patients with heterotopic pancreas in the stomach who underwent CT were not encountered commonly. In addition, most of our subjects were selected from among clinically symptomatic patients who underwent CT because of suspected submucosal tumors. Therefore, our study included symptomatic cases with atypical appearances rather than asymptomatic cases with typical appearances of heterotopic pancreas. Thus, there was a selection bias, since smaller lesions with typical appearances and locations generally were not included in our study. Moreover, helical CT with water as an oral contrast agent was performed in only seven patients, and with the small number of cases that were depicted retrospectively, it was difficult to evaluate the usefulness of this technique for the diagnosis of heterotopic pancreas.

In conclusion, although helical CT with water as an oral contrast agent was helpful in depicting heterotopic pancreas in the stomach, the CT findings of heterotopic pancreas appeared to be nonspecific for the diagnosis, except for its location. Our results suggest that heterotopic pancreas in the stomach is difficult to differentiate from other submucosal tumors at CT. Therefore, we think that endoscopic biopsy should be performed prior to the surgical resection of heterotopic pancreas, and a more conservative approach than surgery should be considered in asymptomatic patients.


   FOOTNOTES
 
Author contributions: Guarantor of integrity of entire study, J.S.C.; study concepts, J.S.C., K.S.S.; study design, J.S.C., D.Y.K.; definition of intellectual content, J.S.C.; literature research, J.S.C., S.T.K.; clinical studies, S.M.N., D.Y.K.; data acquisition, J.S.C., H.Y.K.; data analysis, J.S.C., K.S.S.; manuscript preparation, C.J.S., J.W.K.; manuscript editing, J.S.C.; manuscript review, J.S.C., H.K.K.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 

  1. Pearson S. Aberrant pancreas: review of literature and report of three cases. Arch Surg 1951; 63:168-184.
  2. Lund DP, Compton CC. A 3-week-old girl with pyloric stenosis and an unexpected operative finding. Massachusetts General Hospital Case Records, case 26-1999. N Engl J Med 1999; 341:679-684.[Free Full Text]
  3. Dolan RV, ReMine WH, Dockerty MB. The fate of heterotopic pancreatic tissue: a study of 212 cases. Arch Surg 1974; 109:762-765.[Medline]
  4. Rooney DR. Aberrant pancreatic tissue in the stomach. Radiology 1959; 73:241-244.
  5. Besemann EF, Auerbach SH, Wolf WW. The importance of roentgenologic diagnosis of aberrant pancreatic tissue in the gastrointestinal tract. Am J Roentgenol Radium Ther Nucl Med 1969; 107:71-76.[Medline]
  6. Thoeni RF, Gedgaudas RK. Ectopic pancreas: usual and unusual features. Gastrointest Radiol 1980; 5:37-42.[Medline]
  7. Kilman WJ, Berk RN. The spectrum of radiographic features of aberrant pancreatic rests involving the stomach. Radiology 1977; 123:291-296.[Abstract]
  8. Levine MS, Megibow AJ. Stomach and duodenum: benign tumors. In: Gore RM, Levine MS, Laufer I, eds. Textbook of gastrointestinal radiology. Philadelphia, Pa: Saunders, 1994; 628-659.
  9. Claudon M, Verain AL, Bigard MA, et al. Cyst formation in gastric heterotopic pancreas: report of two cases. Radiology 1988; 169:659-660.[Abstract/Free Full Text]
  10. Ura H, Denno R, Hirata K, Saeki A, Hirata K, Natori H. Carcinoma arising from ectopic pancreas in the stomach: endosonographic detection of malignant change. J Clin Ultrasound 1998; 26:265-268.[Medline]
  11. Winter TC, III, Ager JD, Nghiem HV, Hill RS, Harrison SD, Freeny PC. Upper gastrointestinal tract and abdomen: water as an orally administered contrast agent for helical CT. Radiology 1996; 201:365-370.[Abstract/Free Full Text]
  12. Horton KM, Fishman EK. Helical CT of the stomach: evaluation with water as an oral contrast agent. AJR Am J Roentgenol 1998; 171:1373-1376.[Free Full Text]
  13. Kawamoto K, Yamada Y, Utsunomiya T, et al. Gastrointestinal submucosal tumors: evaluation with endoscopic US. Radiology 1997; 205:733-740.[Abstract/Free Full Text]
  14. Rober HA. Pancreas. In: Schwartz SI, eds. Principles of surgery. 6th ed. New York, NY: McGraw-Hill, 1994; 1401-1432.
  15. Sebastian MW. Benign tumors of the stomach. In: Sabiston DC, Jr, eds. Textbook of surgery: the biological basis of modern surgical practice. 15th ed. Philadelphia, Pa: Saunders, 1997; 868-878.



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